JPH054896A - Production of coating film - Google Patents

Abstract

PURPOSE:To produce a high-hardness coating film excellent in tight adhesion and useful as a protecting film by applying prescribed high-energy light rays to a hydrogenated amorphous carbon film, etc., formed on a base film and mainly composed of carbon and hydrogen and eliminating hydrogen without destruction of the film. CONSTITUTION:A film composed mainly of carbon and hydrogen is formed on a base film having a magnetic recording layer on the substrate by using plasma CVD method, ion-beam vacuum deposition method, etc. The formed film is composed of a hydrogenated amorphous carbon film or a diamond-state carbon film containing 15-35atm.% hydrogen. To the above-mentioned film formed on the base film, light rays having a higher energy (shorter wavelength) than that of the optical absorption edge of this film are applied, e.g. under vacuum or in an inert gas. Hydrogen is eliminated thereby without destruction of the film, thus giving the objective high-hardness protecting film excellent in tight adhesion.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a diamond-like carbon film having high hardness, high adhesion, wear resistance and lubricity, which is useful for a magnetic disk, a magneto-optical disk, a surface protective film for a magnetic head, and the like. The present invention relates to a method for producing a coating such as a hydrogenated amorphous carbon film.

[0002]

2. Description of the Related Art Conventionally, magnetic disks and magnetic heads have been used as magnetic disk devices and magneto-optical disk devices in information storage devices of computer terminals. This magnetic disk is formed by sputtering a magnetic material of ferrite, iron, cobalt, nickel or a compound thereof, a rare earth metal such as neodymium, samarium, gadolinium or terbium, or an alloy thereof onto a substrate such as an aluminum metal plate or plastic. It is manufactured by a method such as forming by a coating method or a coating method. In the magnetic disk device, since the rotation of the magnetic disk is repeatedly stopped during use, the magnetic head and the magnetic disk are repeatedly contacted and worn. This contact wear may damage the magnetic recording layer (magnetic recording medium) of the magnetic disk, resulting in a recording error. Further, both the magnetic recording layer and the magneto-optical recording layer are easily affected by the environment and corroded.

Therefore, a protective film is usually formed on the magnetic (magneto-optical) recording layer in order to prevent such damage and corrosion. As this protective film, silicon dioxide (SiO 2
₂ ), oxides such as alumina (Al ₂ O ₃ ) or carbon films are used. This SiO ₂ and Al ₂ O ₃
The protective coating of can be formed by a sputtering method or a vacuum vapor deposition method. The carbon film is formed by plasma CVD, ion
It can be formed by a beam evaporation method, a sputtering method, or the like.

[0004]

Of the above-mentioned protective coatings, the carbon coating, in particular, has a high hardness, a small friction coefficient, and excellent gas and moisture impermeability. This carbon film is a film mainly containing carbon and hydrogen. However, such a film containing carbon and hydrogen as the main components has a problem that the adhesion to the substrate is not always sufficient. That is, in the conventional coating, film peeling may occur, or the magnetic recording layer and the like may be corroded even if the coating is formed.

An object of the present invention is to produce a coating film which is excellent in adhesion to a substrate while maintaining excellent characteristics such as high hardness and non-permeability of a film containing carbon and hydrogen as main components. To provide a method.

[0006]

As a result of intensive studies to achieve the above-mentioned object, the present inventor found that it is very effective to relieve the internal stress of the film by specific light irradiation. The invention was completed. That is, the present invention is a method for producing a coating film, which comprises a step of forming a film containing carbon and hydrogen as main components on a substrate and irradiating the film with light having energy higher than the optical absorption edge of the film.

Conventionally, as a film containing carbon and hydrogen as main components (carbon film, etc.), a diamond-like carbon film (hereinafter, referred to as
DLC film), hydrogenated amorphous carbon film (hereinafter,
Carbon films such as a-C: H film) are known. These contain several tens of atom% of hydrogen in the film, and if the hydrogen content is different, the properties of the film are also greatly different. For example, an aC: H film containing 50 atom% or more of hydrogen is a polymer-like carbon film that has a large optical band gap and is transparent, but has a relatively low film hardness and a relatively small internal stress. On the other hand, the hardness of the aC: H film containing 15 to 35 atom% of hydrogen is 2000 to 4 in Vickers hardness.
It is very hard at 000 kg / mm ² and has a smooth friction coefficient of 0.2 or less, but the internal stress of the film is -10 ¹⁰ dyn /
It is as large as cm ² . Such internal stress is considered to be caused by the film structure of the film (bonding state of carbon and hydrogen). Then, this internal stress adversely affects the adhesion of the coating. In order to alleviate this internal stress, it is conceivable to anneal the film at 400 ° C. or higher to release hydrogen in the film and reduce the sp ³ structure to increase the sp ² structure. However, annealing at such a high temperature may adversely affect the material of the substrate or the material of the film interposed between the substrate and the protective coating and is not an appropriate means.

On the other hand, in the method of the present invention, the internal stress of the film is relaxed by irradiating the film with light having a higher energy than the optical absorption edge of the film, so that the adhesion is improved without adversely affecting the substrate or the like. be able to. Although there is some unclear point about the mechanism of the decrease of internal stress due to this light irradiation, it is considered that the internal stress of the film is relaxed by dissociating hydrogen and changing the film structure in the bond of carbon and hydrogen.

The manufacturing method of the present invention will be described below in detail along with the steps.

In the method of the present invention, first, a film containing carbon and hydrogen as main components is formed on a substrate. As the substrate,
For example, glass, ceramics, organic resins, metals, etc.
Various members conventionally used by being coated with a material containing carbon and hydrogen as main components can be used, and there is no particular limitation in the present invention. However, it is particularly effective to use a magnetic (magneto-optical) recording layer formed on an appropriate support as a substrate and form a film containing carbon and hydrogen as main components on the substrate. Typical examples of the film containing carbon and hydrogen as the main components include the DLC film and the aC: H film as described above. Further, it is particularly effective to use the aC: H film or DLC film containing 15 to 35 atom% of hydrogen as described above.

The method for forming the film on the substrate is not particularly limited, and includes plasma CVD method, ECR-plasma CVD method (hereinafter referred to as ECR-PCVD method), ion beam evaporation method, ion beam sputtering method, and plasma.・ Various methods such as sputtering method can be used. Also, as the film thickness,
It is preferably about 50 Å to 1 μm. CVD
As the raw material gas used in the method, hydrocarbons such as methane, ethane, propane, ethylene, benzene, and acetylene, which are carbon-containing gases; halogenated hydrocarbons such as methylene chloride, carbon tetrachloride, chloroform, and trichloroethane; methyl. Alcohols such as alcohol and ethyl alcohol,
Ketones such as (CH ₃ ) ₂ CO and (C ₆ H ₅ ) ₂ CO;
CO, CO _{2 and} other gases, and N ₂ and H for these gases
Examples include a mixture of gases such as ₂ , O ₂ , H ₂ O and Ar.

The film containing carbon and hydrogen as main components formed on the substrate as described above is irradiated with light having higher energy than the optical absorption edge of the film. This light irradiation can alleviate the internal stress of the film. The optical absorption edge of a film containing carbon and hydrogen as main components is generally in the range of 0.4 eV to 2.8 eV. Therefore, the light to be irradiated may have a higher energy than this. However, it is more effective to use light having a higher energy than the energy value near the optical absorption edge. Here, regarding the range of irradiation energy, the total energy amount (integrated amount of irradiation light energy) necessary for desorbing hydrogen in the film becomes a problem. Therefore, the energy density and power density of the irradiation light may be appropriately adjusted to the intensity that can achieve the maximum hydrogen desorption effect without destroying the film. The size cannot be specified. The total amount of irradiation energy applied to the film surface is preferably 1 × 10 ³ J / cm ² or more.

Light having a higher energy than the optical absorption edge means light having a shorter wavelength than the wavelength of the optical absorption edge. The light intensity and the irradiation time may take appropriate values as appropriate.
In the present invention, it is preferable to adjust the light intensity by changing it, rather than changing the time. The atmosphere for light irradiation is vacuum, nitrogen, or He, Ne, A
It is desirable to use an inert gas such as r, Kr, or Xe, or a mixed gas of one or more of these. Further, it may be in air depending on the temperature. As a light source of irradiation light, there is an ultrahigh pressure mercury lamp, an Ar ⁺ laser, a He-Cd laser, an excimer laser, or a high energy X-ray source (for example, SOR).

Next, a light irradiation device for carrying out the method of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of a light irradiation apparatus for carrying out the method of the present invention. This light irradiation device includes a substrate holder 2 for mounting the substrate 1 in a chamber 3, and a gas introduction system 4 for introducing a desired gas into the chamber 3. Then, a KrF excimer laser 5 is provided outside the chamber 3, and this laser light can be guided to the window 8 of the chamber 3 via the lens system 6 and the mirror 7 and irradiated onto the substrate 1. The energy distribution of the light with which the substrate 1 is irradiated becomes uniform. Further, the laser light itself may be scanned, or the substrate 1 may be scanned and rotated.

FIG. 2 is a schematic sectional view showing another example of a light irradiation device for carrying out the method of the present invention. This light irradiation device is provided with an Ar ⁺ laser 9, and has a mirror 10 that rotates this light in the X-axis direction and a mirror 11 that rotates this light in the Y-axis direction. The entire surface of the substrate can be irradiated.

The light irradiation device and the film forming device may be integrated so that the film forming and light irradiation steps in the method of the present invention can be continuously performed.

[0018]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Example 1 First, using an ECR-PCVD apparatus schematically shown in FIG. 3, a film containing carbon and hydrogen as main components (hydrogenated amorphous carbon film a-C: H film) was formed.

The ECR-PCVD apparatus shown in FIG. 3 has a cavity resonator type plasma chamber 12, a gas introduction system 13, a microwave introduction window 14, a microwave waveguide 15, and an electromagnet 16.
An Al substrate 17 on which a Co—Ni—P-based recording layer was formed was placed in a substrate holder 18. After this, the inside was evacuated to 1 × 10 ⁻⁷ Torr. Next, CH ₄ : 25 sccm was introduced from the gas introduction system 13, the gas pressure was set to 1 × 10 ⁻⁴ Torr, and then a microwave of 2.45 GHz was introduced from the microwave introduction tube 15 at a power of 900 W. It was introduced through the window 14. At this time, a magnetic field is applied from the outside of the plasma chamber 12 by the electromagnet 16.
An ECR plasma was formed.

The strength of the magnetic field is 1500 gauss at the entrance of the microwave introduction window 14 and 875 at the exit of the plasma chamber.
550 gaus at the position of the base 17 under the ECR condition of gauss
s. Further, by applying an RF bias of 200 W to the base 17 by an RF power source of 13.56 MHz (not shown), a hydrogenated amorphous carbon film (aC: H film) is formed on the base 17 to 1000 angstrom without heating the base 17. Formed thick. When the hydrogen content, film hardness, friction coefficient and internal stress of the aC: H film formed on the Si wafer under the same conditions were evaluated, the hydrogen content (ERDA (Elastic Recoil Detection Analysis)
Is about 25 atom%, the film hardness (evaluated by Knoop hardness meter) is 2000 kg / mm ² , and the friction coefficient (measured by a pin-on-disc method with an Al ₂ O ₃ —TiC alloy sphere having a diameter of 5 mm). Was 0.1 and the internal stress (evaluated by an optical method (disk method)) was 2 × 10 ¹⁰ dyn / cm ² .

Next, a substrate (Co-Ni-P) having the aC: H film formed on the light irradiation apparatus shown in FIG. 1 as described above is formed.
System recording layer, Al-based magnetic disk) as a base holder 2
Then, N ₂ gas was introduced into the chamber 3 from the gas introduction system 4. Subsequently, light from the excimer laser 5 of KrF (pulse width 15 ns, 100 mJ / pulse repetition period 100 Hz) is guided to the window 8 by the lens system 6 and the mirror 7, and the substrate 1 is irradiated with the energy density of 1 mJ / cm ² for 10 seconds. did. Here, a- formed on the Si wafer under the same conditions
C: H film was irradiated with light under the same conditions to obtain hydrogen content, film hardness,
When the friction coefficient and the internal stress were evaluated, the film hardness and the friction coefficient did not change, and the hydrogen content decreased to 5 atom%.
The internal stress was also reduced to 6 × 10 ⁸ dyn / cm ² .

The magnetic disk (aC: H) obtained in this example.
The protective coating of the system, the Co-Ni-P recording layer, and the Al substrate) have excellent adhesion to the protective coating, and in a wear resistance test using a pin-on-disk with a TiC ball, 100,000 of them were dried in air. No peeling or scratching of the film was observed even after rotation, and the coefficient of friction was 0.1 or less.

Example 2 First, using the RF-PCVD apparatus schematically shown in FIG.
In the following manner, a film containing carbon and hydrogen as main components (diamond-like carbon film DLC film) was formed on the substrate.

The RF-PCVD apparatus shown in FIG. 4 is an apparatus equipped with a reaction chamber 19, an electrode 20, a gas introduction system 21, and an exhaust system 22, on which a recording layer of GdTbFeCo (RE-TM alloy) was formed. The glass substrate 23 was placed between the electrodes 20. Then, after exhausting the inside of the reaction chamber 19 to 1 × 10 ⁻⁷ Torr from the exhaust system 22, the gas introducing system 21
CH ₄ : 50 sccm, H ₂ : 15 sccm were introduced, and the gas pressure was 0.015 Torr. Next, the RF power source 2 is placed between the electrodes 20.
RF power of 550 W is applied to the substrate 23, and a negative bias of −300 V is applied to the substrate 23 by the DC power source 25 to heat the substrate to 200 ° C. and the diamond-like carbon film (DLC film) is formed to a thickness of 1000 angstroms. Formed thick.

The hydrogen content, film hardness, friction coefficient and internal stress of the DLC film formed on the Si wafer under the same conditions were evaluated in the same manner as in Example 1. The hydrogen content was 20 atom%. , Film hardness = 2500kg / m
m ² , friction coefficient = 0.15, internal stress = 8 × 10 ⁹ dyn / cm
^{Was 2} .

Next, the substrate (GdTbFeCo recording layer, glass-based magnetic disk) on which the DLC film was formed as described above was irradiated with light using the same apparatus as in Example 1. However, as the light source, not the KrF excimer laser 5, but the light from a 100 W ultra-high pressure mercury lamp was dispersed and a bright line of 365 nm was used. The irradiation power density on the film surface was set to 20 mW / cm ² and irradiation was performed for 15 hours. Here, the DLC film formed on the Si wafer under the same conditions was irradiated with light under the same conditions, and the hydrogen content, the film hardness, the friction coefficient, and the internal stress were evaluated. The film hardness and the friction coefficient did not change. , The hydrogen content was reduced to 8 atom%, and the internal stress was 7 × 10 ⁸ dyn /
It was reduced to cm ² .

The magnetic disk (DLC-based protective coating, GdTbFeCo-based recording layer, glass substrate) obtained in this example has excellent adhesion of the protective coating, and the same good performance as in Example 1 was obtained. .

Example 3 First, an aC: H film was formed on a substrate in the same manner as in Example 1. Next, using the light irradiation device shown in FIG. 2, light irradiation was performed on the base body (Co—Ni—P recording layer, Al base magnetic disk) on which the aC: H film was formed. The irradiation method was performed by scanning the light of the Ar ⁺ laser 9 on the substrate 1 by the X-axis direction rotating mirror 10 and the Y-axis direction rotating mirror 11 and irradiating the entire surface of the substrate. At this time, the laser was adjusted to have a power density of 10 ⁶ W / cm ² and irradiated for 20 ms. With the coating film obtained as described above, the same good performance as in Example 1 was obtained.

[0030]

As described above, in the method of the present invention, the internal stress of the coating is relaxed by irradiating the coating with light having a higher energy than the optical absorption edge of the coating, which adversely affects the substrate and the like. Adhesion can be improved without giving. That is, the coating film obtained by the method of the present invention maintains excellent characteristics such as high hardness and non-permeability of a film containing carbon and hydrogen as main components, and further has excellent adhesion to a substrate. Becomes If the adhesion of the protective coating is improved, it is possible to favorably prevent the protective coating from peeling off or the corrosion of the magnetic recording layer or the like in a magnetic (magneto-optical) disk or the like.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a light irradiation device for carrying out the manufacturing method of the present invention.

FIG. 2 is a schematic cross-sectional view showing another example of a light irradiation device for carrying out the manufacturing method of the present invention.

FIG. 3 ECR-PCVD used in Examples 1 and 3
It is sectional drawing which shows a device typically.

FIG. 4 is a cross-sectional view schematically showing the RF-PCVD apparatus used in Example 2.

[Explanation of symbols]

1 substrate 2 substrate holder 3 chamber 4 gas introduction system 5 KrF excimer laser 6 lens system 7 mirror 8 window 9 Ar ⁺ laser 10 X-axis rotating mirror 11 Y-axis rotating mirror 12 cavity resonator (plasma chamber) 13 gas Supply system 14 Microwave introduction window 15 Microwave introduction tube 16 Electromagnet 17 Base 18 Base holder 19 Reaction chamber 20 Electrode 21 Gas introduction system 22 Exhaust system 23 Base 24 RF power supply 25 DC power supply

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G11B 5/187 E 6789-5D 5/72 7215-5D // G11B 11/10 A 9075-5D

Claims (3)

[Claims] 1. A method for producing a coating film, which comprises a step of forming a film containing carbon and hydrogen as main components on a substrate and irradiating the film with light having energy higher than an optical absorption edge of the film. 2. The manufacturing method according to claim 1, wherein the film containing carbon and hydrogen as main components is a hydrogenated amorphous carbon film containing 15 to 35 atom% of hydrogen. 3. The manufacturing method according to claim 1, wherein the film containing carbon and hydrogen as main components is a diamond-like carbon film.