JP3000210B2 - Method for forming carbon or carbon-based coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a surface of a solid having carbon or carbon-based film having an optical energy bandwidth of 1.0 eV or more, particularly 1.5 to 5.5 eV, on a surface to be formed. And a composite which seeks to obtain a reinforcing material or a protective material against mechanical stress.

[0002]

2. Description of the Related Art With respect to coating of a carbon film, a patent application “composite having a carbon film and a method for producing the same” filed by the present inventors (Japanese Patent Application No. 56-146936, filed on May 17, 1981). It has been known.

[0003] The carbon film is not only a wear-resistant material but also has many characteristics such as high smoothness and high thermal conductivity, and is expected to be applied to electric parts and the like.

On the surface to be formed, carbon or carbon having an amorphous (amorphous) structure similar to diamond or a semi-amorphous (semi-amorphous) structure having microcrystallinity of 5 to 200 mm is deposited. In the case of forming a film containing a main component, in the vicinity of a high-frequency application electrode provided with a substrate having a surface to be formed, positive ions accelerated by self-bias generated by accumulation of electrons in plasma in the high-frequency application electrode ( For example, by colliding H ⁺ ) with carbon or a film containing carbon as a main component, the carbon film containing carbon or carbon as a main component is formed into a carbon film having a higher hardness and a structure close to diamond. I've been making things. This is because positive ions collide with C
= C by reducing the proportion of carbon having a double bond such as C
By increasing the number of carbons that can bond to --C or eliminating hydrogen atoms bonded to carbon atoms, so-called three-way carbons with sp ² hybridized orbitals or so-called two-way carbons with sp hybridized orbitals are eliminated, and sp ³ hybridized This is because diamond bonding is easily caused by increasing the ratio of so-called tetragonal carbon having orbits.

Therefore, when attempting to form a carbon film having a higher hardness or a film containing carbon as a main component, it is necessary to increase the self-bias generated in the vicinity of the high frequency application electrode to increase the acceleration of positive ions.

As a method for increasing the self-bias, there is firstly a method for reducing the reaction pressure. This is because the number of hydrocarbon gas molecules contained in a unit volume is reduced by reducing the pressure of carbon or the hydrocarbon gas used to form a film containing carbon as a main component, and the gas is relatively decomposed. This is based on the fact that the output of the high-frequency energy applied to the plasma increases to increase the electrons in the plasma and accumulate in the high-frequency application electrode, thereby increasing the cell bias.

There is also a method of increasing the output of high-frequency energy. However, as described above, when the energy for decomposing gas increases, the electrons in the plasma increase. This is because the self-bias increases due to the increase.

[0008]

However, it is completely known that when forming a film containing carbon or carbon as a main component, the film is formed by adding an additive such as hydrogen or oxygen to increase the self-bias. Absent.

The present invention has been made based on the finding that the addition of an additive such as hydrogen or oxygen when forming a coating containing carbon or carbon as a main component increases the self-bias. Alternatively, the purpose is to form a coating containing carbon as a main component.

[0010]

SUMMARY OF THE INVENTION Based on the above findings, the present invention provides a method for forming a first substrate provided in contact with a substrate having a surface to be formed.
DC or high-frequency energy is applied between the first electrode and the second electrode, and the generated plasma causes a decomposition reaction between the hydrocarbon gas or the additive gas and the carbon gas on the surface to be formed. In the method of forming a film, hydrogen or oxygen is added when forming a carbon film.

[0011] Further, the present invention provides a method for applying a direct current or a high frequency energy between a first electrode and a second electrode provided in contact with a substrate having a surface to be formed, and generating the hydrocarbon by a plasma generated. In the method of forming a carbon film on the surface to be formed by subjecting a gas and / or an additive gas to a decomposition reaction to form a carbon film on the formation surface, the carbon film is formed by changing the amount of hydrogen or oxygen added. The hardness of carbon or a film containing carbon as a main component is increased from the surface on which the carbon is formed to the surface of the carbon film. Hereinafter, the present invention will be described specifically with reference to Examples.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of a plasma CVD apparatus for forming carbon or a film containing carbon as a main component according to the present invention.

In the doping system (1) of FIG. 1, hydrogen or oxygen as an additive is converted from (2), and a hydrocarbon gas such as methane or ethylene as a reactive gas is converted from (3) to diborane (III) impurity. Hydrogen dilution) (4), V-impurity ammonia or phosphine from (5) valve (6), flow meter
After passing through (7), it is introduced into the reaction system (8) through the nozzle (9).
Before reaching the nozzle, it is effective to add microwave energy (10) to excite the reactive gas to activate it in advance.

The reaction system (8) was provided with a first electrode (11) and a second electrode (12). A high frequency power supply (13), a matching transformer (14), and a DC bias power supply (1) are provided between the pair of electrodes (11) and (12).
5) Electric energy is applied to generate plasma.
The exhaust system (16) has a pressure regulating valve (17) and a turbo molecular pump (1
8) The unnecessary gas is exhausted through the rotary pump (19).

When the pressure in the reaction space (20) is 0.001 to 10 torr, typically 0.01 to 0.5 torr, an energy of 0.1 to 5 kW is applied to the reactive gas by high frequency or DC energy.

[0016] In particular, the excitation source is 1GH _Z or more, for example 2.45GH _Z
In the frequency, to separate hydrogen from the CH bond, further frequency source CC bonds In the frequency of 0.1 ~50MH _Z for example 13.56 MHz, to decompose the C = C bond, make -CC- bond, Unpaired carbon atoms can collide with each other to form a covalent bond to form a structure locally having a stable diamond structure.

DC bias is -200 to 600V (effectively -4
00 to + 400V). This is because when the DC bias is zero, the self-bias has -200 V (the second electrode is at the ground level).

As the hydrocarbon gas, methane (C
H _4), ethane (C ₂ H _6), ethylene (C ₂ H _4), methane hydrocarbon (C _n H _{2n + 2)} gas or silicon if included in a part of such tetramethylsilane (( CH ₃ ) ₄ Si), tetraeralsilane
It may be silicon carbide such as ((C ₂ H ₅ ) ₄ Si) or carbon chloride such as carbon tetrachloride (CCl ₄ ).

The first electrode had a cooling means, and the temperature on the surface to be formed was kept at 250 to -100 ° C.

The surface to be formed used in the present invention is P
ET (polyethylene terephthalate), PES, PMM
A, an organic resin substrate such as Teflon, epoxy, polyimide or the like, a metal mesh carrier, a tape carrier such as paper, glass, metal, ceramic, semiconductor, a member for a magnetic head, a magnetic disk, and the like. .

FIG. 2 shows that methane is produced in the apparatus shown in FIG.
This graph shows the change in self-bias when the amount of hydrogen or oxygen added was changed under the conditions of a flow rate of 100 SCCM, high-frequency energy of 60 W, and a reaction pressure of 10 Pa.

It is apparent that the self-bias is clearly increased when hydrogen or oxygen is added. As a comparison, addition of NF ₃ indicates that the self-bias is conversely small.

FIG. 3 shows a system similar to FIG. 2 in which methane is introduced at a flow rate of 100 SCCM in the apparatus shown in FIG.
6 shows the relationship between the amount of hydrogen or oxygen added and Vickers hardness when a film is formed for 15 minutes at a reaction pressure of 10 Pa with 600 W applied. It has been shown that by adding hydrogen or oxygen, a carbon film having a high Vickers hardness or a film containing carbon as a main component can be obtained. Again, the change in Vickers hardness due to the addition of NF ₃ was compared, but conversely, the Vickers hardness decreased with the addition amount.

FIG. 4 shows the relationship between the amount of hydrogen or oxygen added and the film thickness of carbon or a film containing carbon as a main component, which was formed under the same conditions as those shown in FIG. Although it is shown that the film thickness is reduced by the addition of hydrogen or oxygen, the result of an experiment under the same conditions using NF ₃ shown in FIG. 5 shows that the film thickness increases with the addition amount.

Further, the present invention is intended to coat carbon or a film containing carbon as a main component on the surface to be formed to reinforce mechanical strength such as abrasion resistance on the surface.
For this purpose, instead of directly forming a carbon film having a hardness similar to diamond or a film containing carbon as a main component on the surface to be formed, the hardness is gradually increased from a portion close to the surface to be formed, and a desired hardness is obtained. It is characterized in that the addition amount of the additive gas is changed so that carbon or a film containing carbon as a main component having a desired hardness can be obtained when the film thickness is large.

In order to form a film having a hardness similar to diamond directly on the surface to be formed, the self-bias must be increased to form a film containing carbon or carbon as a main component. Sputtering on the surface to be formed cannot be avoided, but carbon or a film containing carbon as a main component that is close to the surface to be formed has a hardness of carbon that can be formed with a self-bias that does not damage the surface to be formed. Alternatively, a film containing carbon as a main component is formed, and a film whose hardness is gradually increased is laminated, and a carbon film having a desired hardness or a film containing carbon as a main component is formed on the surface. Carbon or a coating containing carbon as a main component, which has good close contact with carbon and has high hardness.

In this case, by changing the method of laminating a film having a small hardness from a film having a high hardness into several layers and continuously changing the hardness, carbon or carbon having a continuously changed hardness in a single layer is removed. There is a method of forming a coating as a main component.

In the present invention, the surface to be formed is placed on the cathode electrode. This is because, when comparing the film quality of the carbon film formed when the surface to be formed is placed on the anode side and when the film surface is placed on the cathode side, the carbon film having the higher hardness when the surface to be formed is placed on the cathode side is used. This is because a film can be obtained at a high deposition rate.

As described above, a Vickers hardness of 2000 kg / mm ² or more is formed on the surface to be formed by the plasma.
Amorphous carbon with a large number of CC bonds with thermal conductivity of 2.5 W / cm deg or higher was formed. In addition, this electromagnetic energy is 50
Supplying W ~1KW, it was added plasma energy 0.03~3W / cm ² per unit area.

[0030]

【Example】

Example 1 In the apparatus shown in FIG. 1, a carbon film was formed on a substrate having a surface to be formed by the method of the present invention.

First, methane to which hydrogen was added at a flow rate of 10 SCCM of hydrogen and methane at a flow rate of 100 SCCM from a nozzle was introduced into the reaction system, the pressure was maintained at 0.03 torr, high frequency energy of 50 W was applied to methane, and self-biasing was performed. A film was formed on an Si substrate kept at room temperature under the condition of -150 V for 150 minutes to form a first layer. Next, 50SCC hydrogen from nozzle
M, methane was introduced at a flow rate of 100 SCCM with methane to which hydrogen was added, and the pressure was maintained at 0.015 torr.
00W high frequency energy, and self bias -20
The film was formed for 150 minutes while the surface to be formed was kept at 150 ° C. under the condition of 0 V to form a second layer.

Then, hydrogen was supplied to the second layer from the nozzle by 80 SC.
CM and methane were introduced at a flow rate of 100 SCCM with methane to which hydrogen was added, the reaction system was maintained at 0.015 torr, high-frequency energy of 200 W was applied to methane, and self-bias-2
A film was formed for 60 minutes while the surface to be formed was kept at room temperature under the condition of 80 V to form a third layer. When the Vickers hardness of these three layers was measured, the first layer was 2200 kg / mm ² ,
The layer was 3500 kg / mm ² and the third layer was 4200 kg / mm ² , and a carbon film having a hardness similar to diamond on the surface could be formed with good adhesion to the surface to be formed.

Example 2 Oxygen was added to the reaction system from the nozzle by 10
SCCM, methane was introduced at a flow rate of 100 SCCM with oxygen-added methane, the pressure was maintained at 0.03 torr, and 5
0 W high frequency energy is applied, and the self-bias is -150.
A film was formed on an Si substrate kept at room temperature under the condition of V for 150 minutes to form a first layer. Next, oxygen from the nozzle
50 SCCM, methane is introduced at a flow rate of 100 SCCM with methane to which oxygen is added, and while maintaining the pressure at 0.015 torr, high-frequency energy of 100 W is applied to methane, and self-biasing is performed.
The surface to be formed is kept at 150 ° C. under the condition of 200 V,
A film was formed for 2 minutes to form a second layer. Then, methane to which oxygen was added was introduced from the nozzle at a flow rate of 80 SCCM and methane at a flow rate of 100 SCCM on the second layer. The film was formed for 60 minutes while maintaining the surface to be formed at room temperature under the condition of a bias of -280 V to form a third layer.

When the Vickers hardness of these three layers was measured, the first layer was 2000 kg / mm ² , and the second layer was 330 kg / mm ² .
0 kg / mm ² and the third layer was 4000 kg / mm ² , and a carbon film having a hardness similar to diamond on the surface could be formed with good adhesion to the surface on which the film was formed.

Example 3 Hydrogen-added methane was introduced at a flow rate of 30 SCCM and methane at a flow rate of 100 SCCM into a reaction system on which a substrate having a surface to be formed was placed, and the pressure was maintained at 0.03 torr. 100 W of high frequency energy is added to methane,
A film was formed for 50 minutes to form a first layer. Then the first
A second layer was formed on the first layer under the same conditions as the first layer except that the flow rate of hydrogen was 50 SCCM.

Then, on the second layer, the flow rate of hydrogen is 80 SCCM.
The conditions were the same as in the first layer except that As a result, 2400Kg / mm ² , 3400Kg / mm ² , 4200Kg / m
A carbon film comprising a first layer, a second layer, and a third layer having a Vickers hardness of m ² was formed. This carbon film had a surface hardness of 4200 Kg / mm ² , similar to diamond, and was excellent in wear resistance, high thermal conductivity and high smoothness.

In this embodiment, the hardness of the carbon film is increased by increasing only the flow rate of hydrogen, but the same effect can be obtained by reducing the flow rate of methane.

In this embodiment, each carbon film layer is formed by using one reaction chamber. However, each layer may be formed in a different reaction chamber by connecting a plurality of reaction chambers.

Example 4 Oxygen-added methane was introduced at a flow rate of 30 SCCM and methane at a flow rate of 100 SCCM into a reaction system on which a substrate having a surface to be formed was placed, and the pressure was maintained at 0.03 torr. 100 W of high frequency energy is added to methane,
A film was formed for 50 minutes to form a first layer. Then the first
A second layer was formed on the first layer under the same conditions as the first layer except that the flow rate of oxygen was 50 SCCM. Then, on the second layer, the same conditions as in the first layer were used except that the flow rate of oxygen was 80 SCCM.

As a result, 2200 kg / mm ² and 3100 kg / m
A carbon film comprising a first layer, a second layer and a third layer having a Vickers hardness of m ² and 4000 kg / mm ² was formed. This carbon film has a surface hardness of 4000 kg / mm ^2.
And hardness similar to diamond and excellent in wear resistance, high thermal conductivity and high smoothness.

In this embodiment, the hardness of the carbon film is increased by increasing only the flow rate of oxygen, but the same effect can be obtained by decreasing the flow rate of methane.

In this embodiment, each carbon film layer is formed using one reaction chamber, but each layer may be formed in a different reaction chamber by connecting a plurality of reaction chambers.

[Embodiment 5] In this embodiment, instead of laminating layers having different hardnesses on the surface to be formed, the hardness is continuously changed by continuously increasing the amount of added hydrogen. Carbon film was formed.

First, film formation was started under the same conditions as those for forming the first layer in Example 1, and thereafter the amount of hydrogen added was changed.
A carbon film was formed on the surface to be formed by increasing the rate at a rate of 0.5 to 10 SCCM / min until it reached 100 SCCM. The formed carbon film had a Vickers hardness of 4200 kg / mm ^{2 on} the surface and was excellent in wear resistance, high thermal conductivity and high smoothness.

In this embodiment, only the flow rate of hydrogen is continuously increased. However, the flow rate of methane alone may be continuously reduced, or the present invention may be implemented by changing hydrogen to oxygen.

[Embodiment 6] In this embodiment, before forming a carbon film on a formation surface, the formation surface is arranged in an atmosphere of oxygen atoms activated by ultraviolet light and ozone generated by ultraviolet light. Thus, a carbon film was formed after removing organic contaminants or foreign substances on the surface to be formed.

The organic contaminants on the surface to be formed are the biggest cause of lowering the adhesion between the film and the film formed thereon. FIG. 6 shows the apparatus used in this example. FIG. 6 shows a combination of the reaction chamber (24) shown in FIG. 1 and a preliminary chamber (25) for creating an atmosphere of oxygen atoms activated by ultraviolet light and ozone generated by ultraviolet light. Reaction room (24) and spare room
A gate valve (23) is provided between the gate valve (23). Low-pressure mercury lamp (185 nm, 254 nm) (21), shutter (22)
Is provided.

In the preliminary chamber (25), active oxygen and ozone are generated by the following reaction, which removes organic contaminants on the surface to be formed. O ₂ + hν (185 nm) → O + O O ₂ + O → O ₃ O ₃ + hν (254 nm) → O ^* + O ₂ O ₃ + C _n H _m O _k → CO, CO _2, H ₂ OO ^* + C _n H _m O _k → CO, CO _2, H ₂ O

[0049] That is to decompose and remove organic substances on the formation surface (C _n H _m O _k) by the combined action of ultraviolet light energy and ultraviolet ozone and activated generated by external light oxygen atoms.

In operation, first, a substrate having a surface to be formed is set in a preliminary chamber, and then a low-pressure mercury lamp is turned on.
Organic substances on the formation surface were decomposed and removed. The low-pressure mercury lamp may be turned on in advance and the shutter (22) may be opened. Then turn off the lamp (shutter may be closed)
The pressure in the preparatory chamber was reduced, and when the same pressure was reached in the reaction chamber, the gate valve (23) provided between the reaction chamber and the reaction chamber was opened.
The substrate was transferred to the reaction chamber.

After the above processing, the embodiment 1, embodiment 2, embodiment 3, embodiment 4 or embodiment 5 is formed on the surface to be formed.
A carbon film was formed according to the following. The obtained carbon film had extremely excellent adhesion to the surface on which it was formed.

The above method has an excellent effect in that a film can be formed in a reaction chamber in a short time without exposure to the air after removing contaminants such as organic substances.

In the above embodiment, only one type of additive is shown, but the effect of the present invention can be obtained even if two or more types are mixed and added.

[0054]

As described above, carbon or a film containing carbon as a main component produced by the method of the present invention is formed with a self-bias that does not damage the surface to be formed by changing the amount of added hydrogen or oxygen. A carbon or carbon-based film having the desired hardness is formed, and a film having a gradually increased hardness is laminated, and a carbon- or carbon-based film having a desired hardness is formed on the surface. Therefore, it has a hardness similar to diamond with excellent adhesion to the surface to be formed, and is used as an electrical member that travels by rubbing the surface of a dissimilar material on a part such as a magnetic head or a magnetic disk. It was very effective.

Particularly, the obtained carbon or a coating containing carbon as a main component has a thermal conductivity of 2.5 W / cm deg or more, typically 4.0 W / cm deg.
~ 6.0W / cm deg and close to 60W / cm deg of diamond, it is possible to uniformly dissipate the heat generated by friction, and furthermore, it has abrasion resistance, high thermal conductivity, high smoothness unique to carbon film, etc. It had characteristics.

Further, the method of the present invention comprises the steps of:
The application can be immeasurable because a magnetic material, a metal, a ceramic, a semiconductor, or the like can be used as a formation surface.

[Brief description of the drawings]

FIG. 1 shows the outline of the apparatus used in the present invention. FIG. 2 is a diagram showing a self-bias with respect to the flow rates of hydrogen and oxygen.
FIG. 3 is a view showing the relationship between the addition flow rate and Vickers hardness. 4 and 5 are diagrams showing the relationship between the addition flow rate and the film thickness. FIG. 6 is a diagram showing an apparatus used in Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Doping system 6 ... Valve 7 ... Flow meter 8 ... Reaction system 9 ... Nozzle 10 ... Microwave energy 11 ... 1st electrode 12 ... 2nd Electrode 13 High frequency power supply 14 Matching transformer 15 DC bias power supply 16 Exhaust system 17 Pressure regulating valve 18 Turbo molecular pump 19 Rotary pump 20 Reaction space

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI G11B 5/72 G11B 5/72 5/84 5/84 B

Claims (3)

(57) [Claims] 1. Decomposition of a hydrocarbon gas by plasma
In response, carbon or magnetic head
In the method of forming a coating containing carbon as a main component, when forming the coating, the magnetic head or the magnetic disk may be used.
Add hydrogen or oxygen while keeping the temperature below 250 ° C
And carbon or carbon with a thermal conductivity of 2.5 W / cm deg or more.
A method of forming a coating as a component. 2. A method for decomposing a hydrocarbon gas by plasma.
In response, carbon or magnetic head
In the method of forming a film containing carbon as a main component, when forming the film, the amount of hydrogen or oxygen to be added is determined.
From the surface to the surface of the coating containing carbon or carbon as the main component
Mainly carbon or carbon characterized by increasing
A method of forming a coating as a component. 3. Carbon or charcoal formed according to claim 2.
The hardness of the coating mainly composed of silicon
Large toward the surface of the coating containing silicon or carbon as the main component
Carbon or a carbon-based material characterized by
A method of forming a film.