JPH01246115A - Method for forming coating film of carbon or material composed mainly of carbon - Google Patents

Abstract

PURPOSE:To obtain a coating film of carbon or a material composed mainly of carbon and having high hardness by decomposing a hydrocarbon gas with a plasma generated between electrodes and adding hydrogen or oxygen to the decomposition product to form a carbon film. CONSTITUTION:A DC or high-frequency electric energy is applied between the 1st electrode and the 2nd electrode placed close to a substrate having a surface to be treated. A hydrocarbon gas or a mixture of the hydrocarbon and an additive gas is decomposed by the plasma generated by the above electric energy to form a carbon film on the surface of the substrate. In the above process, hydrogen or oxygen is added to the system in the formation of the carbon film. The hydrocarbon gas may be hydrocarbons such as methane, ethylene or alkane hydrocarbon, a silicon carbide such as tetramethylsilane in the case containing silicon as a part of the component, or a chlorinated carbon such as carbon tetrachloride. The bias is increased by the addition of hydrogen or oxygen to form a coating film having high Vickers hardness.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Application of the Invention" The present invention is applicable to optical energy band widths of 1. By coating a surface to be formed with carbon or a film made of carbon having a voltage of OeV or higher, particularly 1.5 to 5.5 eV, it is attempted to obtain a reinforcement material for the surface of these solids or a protective material against mechanical stress. It concerns complexes.

[Prior Art] Regarding carbon film coating, the patent application filed by the present inventor is entitled "Composite with Carbon Film and Method for Preparing the Same"
(Japanese Patent Application No. 146936/1982 filed on May 17, 1982) is known.

In addition, carbon films are wear-resistant materials and have many properties such as high smoothness and high thermal conductivity, and are expected to be used in electrical parts and other applications.

The main component is carbon, which has an amorphous (non-crystalline) structure with a hardness similar to that of diamond or a semi-amorphous (semi-amorphous) structure with a microcrystalline size of 5 to 200 people on the surface to be formed. When forming a film that has a surface to be formed, positive ions (for example, 1 M By colliding with carbon or a film whose main component is carbon that is being formed, the carbon film is made to have a harder structure similar to that of diamond. It's here. This is done by bombarding positive ions to reduce the proportion of carbons with double bonds such as C-C and increase the number of carbons that form C-C bonds, or to reduce the hydrogen atoms bonded to carbon atoms. This is to make it easier to form diamond bonds by eliminating the so-called trigonal carbons having sp2 hybrid orbitals and the so-called tetragonal carbons having sp3 hybrid orbitals and increasing the proportion of so-called tetragonal carbons having sp3 hybrid orbitals.

Therefore, when trying to create carbon with greater hardness or a film mainly composed of carbon, it is necessary to increase the self-bias generated near the high-frequency application electrode to increase the acceleration of positive ions.

The first method used to increase this self-bias is to reduce the reaction pressure. This is because by reducing the pressure of the hydrocarbon gas used to form carbon or carbon-based coatings, the number of hydrocarbon gas molecules contained in a unit volume decreases, so the gas is relatively decomposed. This is based on the fact that the output of high-frequency energy applied for this purpose increases, and the number of electrons in the plasma increases and is accumulated in the high-frequency application electrode, resulting in an increase in self-bias.

There is also a method of increasing the output of high frequency energy, but as mentioned above, as the energy for decomposing gas increases, the number of electrons in the plasma increases, so the accumulation of electrons in the high frequency application electrode increases. This is due to an increase in self-bias.

[Problems with conventional technology]

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

The present invention was made based on the knowledge that self-bias increases when an additive such as hydrogen or oxygen is added when forming carbon or a film mainly composed of carbon. The purpose is to create a film containing the main component.

[Means to solve the problem]

Based on the above findings, the present invention applies direct current or high frequency energy between a first electrode and a second electrode provided in contact with a substrate having a surface to be formed, and generates plasma to generate hydrocarbons. In the method of forming a carbon film on the surface to be formed by decomposing and reacting gas or an additive gas in addition to the gas, the method includes adding hydrogen or oxygen when forming the carbon film, and adding hydrogen or oxygen to the first electrode. Direct current or high frequency energy is applied between the substrate and the second electrode provided in contact with the substrate having the surface to be formed, and the generated plasma causes a decomposition reaction of the hydrocarbon gas or the additive gas. At least in the method of forming a carbon film on the surface to be formed, the hardness of carbon or a film mainly composed of carbon is adjusted by changing the amount of hydrogen or oxygen added when forming the carbon film. It was decided to increase it from the surface side toward the surface of the carbon film.

The present invention will be specifically explained below along with Examples.

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 drawing, in the doping system (1), the additive hydrogen or oxygen is added to (2), the reactive gas such as hydrocarbon gas such as methane or ethylene is added to (3), and the valent impurity diporane (hydrogen diluted) is added to the doping system (1). ) (4), the heptavalent impurity ammonia or phosphin is added to the valve (6) from (5),
It passes through a flow meter (7) and is introduced into the reaction system (8) through a nozzle (9). It is effective to preactivate the reactive gas by applying microwave energy at 00) for excitation of the reactive gas before reaching this nozzle.

The reaction system (8) was provided with a first electrode 00 and a second electrode surface. A high frequency power source (1
3), Matching transformer 04), electric energy is applied from the DC bias power supply side, and plasma is generated. The exhaust system 06) exhausts unnecessary gas through a pressure regulating valve 07), a turbo molecular pump 08), and a rotary pump (19).

The reactive gas has a pressure in the reaction space 12 [D] of 0°001 to 10 torr, typically 0.01 to 0.5 torr.
0 due to energy from high frequency or direct current under rrO
．． A weak amount of energy is added to 1 to 5.

In particular, when the excitation source has a frequency of IGH2 or higher, for example 2.45 Gll□, hydrogen is separated from the C-H bond, and the frequency source is 0.1 to 50 MHz, for example 13.56 MHz.
At the frequency of z, C-C bonds and C=C bonds are decomposed to create -C-C- bonds, and the unpaired bonds of carbon collide with each other to covalently bond, creating a stable diamond structure. It may have a locally formed structure.

DC bias is -200 to 600V (substantially -4
00~+400V). This is because when the DC bias is zero, the self-bias has a voltage of 1200V (with the second electrode at the ground level).

Examples of hydrocarbon gases include gases such as methane (CH4), ethane (C2H6), ethylene (C2H4), and methane-based hydrocarbons (CnH2, 2), or tetramethylsilane (if silicon is partially included). (CH3) 4s
i), silicon carbide such as tetraeralsilane ((CzHs) n5i), or carbon tetrachloride (CC1,
) may also be carbon chloride.

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

Examples of the surface to be formed used in the present invention include organic resin substrates such as PET (polyethylene terephthalate), PES, PMMA, Teflon, epoxy, polyimide, metal mesh carriers, paper note tape carriers, glass, metals, ceramics, etc. Examples include semiconductors, magnetic head members, and magnetic disks.

Figure 2 shows that methane is 10Q S in the apparatus shown in Figure 1.
This figure shows the change in self-bias when the amount of hydrogen or oxygen added was changed under the conditions of introducing at a flow rate of CCM, applying high frequency energy of 6 ON, and reaction pressure of 10 Pa.

It is shown that the self-bias clearly increases when hydrogen or oxygen is added. NF3 for comparison
However, it has been shown that the self-bias becomes smaller.

Also, Figure 3 shows the addition of hydrogen or oxygen when methane was introduced at a flow rate of 1003 CCH in the apparatus shown in Figure 1 as in Figure 2, high frequency energy of 600 W was applied, and film was formed for 15 minutes at a reaction pressure of 10 Pa. The relationship between quantity and Vickers hardness is shown. It has been shown that by adding hydrogen or oxygen, it is possible to obtain a carbon or carbon-based coating having a high Vickers hardness. Here, we also compared the change in Vickers hardness due to the addition of NF, 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 mainly composed of carbon, which was prepared under the same conditions as shown in FIG. 3. Although it has been shown that the film thickness becomes thinner due to the addition of hydrogen or oxygen, the results of an experiment using NF3 shown in FIG. 5 under the same conditions show that the film thickness becomes thicker as the amount of addition increases.

In addition, the present invention aims to strengthen mechanical strength such as wear resistance on the surface by coating carbon or a film mainly composed of carbon on the surface to be formed. Rather than directly forming carbon or a film mainly composed of carbon on the surface to be formed,
The hardness gradually increases from the part that is in close contact with the surface to be formed,
The method is characterized in that the amount of the additive gas added is varied so that a film having a desired hardness and carbon or a film mainly composed of carbon is obtained at a desired film thickness.

In order to directly form a film with hardness similar to diamond on the surface to be formed, it is necessary to increase the self-bias to form carbon or a film mainly composed of carbon. Although sputtering cannot be avoided, carbon or a carbon-based film that is in close contact with the surface to be formed must be made of carbon or carbon with a hardness that can be created with a self-bias that does not damage the surface to be formed. If you start with a film containing carbon as the main component, then layer films with gradually increasing hardness to form carbon or a film mainly composed of carbon with the desired hardness on the surface. It is possible to form carbon or a film mainly composed of carbon, which has good properties and high hardness.

In this case, the method of laminating films in several layers, starting from the film with the lowest hardness and the film with the highest hardness, and by continuously changing the hardness, the main component is carbon or carbon whose hardness changes continuously within a single layer. There is a method of forming a film that

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 it is placed on the cathode side, the hardness of the carbon film is greater when the surface to be formed is placed on the cathode side. This is because the film can be obtained at a high deposition rate.

As described above, an amorphous structure or a microcrystalline structure having a Vickers hardness of 2000 Kg/mm or more and a large number of C-C bonds with a thermal conductivity of 2.5 W/cm deg or more is formed on the surface to be formed by plasma. Carbon with an amorphous structure was produced. Furthermore, this electromagnetic energy was supplied at 50 W to IKI/I, and plasma energy of 0.03 to 3 W/cm2 per unit area was applied.

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

First, methane to which hydrogen was added was introduced into the reaction system through a nozzle at a flow rate of IOSCCM of hydrogen and 1005 CCH of methane, and the pressure was maintained at 0.03 torr.
Apply 0W high frequency energy and self-bias -150
Film formation was performed for 150 minutes on a Si substrate maintained at room temperature under the condition of V to form a first layer. Next, hydrogen-added methane was introduced through the nozzle at a flow rate of 505 CCM of hydrogen and 100 SCCM of methane, and the pressure was increased to 0.015 t.
A second layer was formed by applying too much high frequency energy to methane while maintaining the temperature at a temperature of 100°C, and holding the surface to be formed at 150°C at a self-bias of -200°C for 150 minutes to form a second layer. Then, 803 ml of hydrogen is applied to the second layer from a nozzle.
CC1'! , hydrogen-added methane was introduced at a flow rate of 1005 CCM, and the reaction system was heated to 0.015 torr.
A high frequency energy of 200 W was applied to the methane while the temperature was maintained at -280 mm, and a film was formed for 60 minutes while the surface to be formed was kept at room temperature under the condition of a self-bias of -280 mm to form a third layer. The Vickers hardness of these three layers was measured to be 2200 h/mm” for the first layer and 3500 Kg for the second layer.
/mm2, and the third layer had a hardness of 4200 Kg/mm2, making it possible to form a carbon film with hardness similar to that of diamond on the surface with good adhesion to the surface on which it was formed.

[Example 2] Oxygen was added to the reaction system through a nozzle at IOSCCM, and methane was added at 10
introducing oxygenated methane at a flow rate of 05 CCH;
Maintain pressure at 0.03 torr and apply 50W to methane
A first layer was formed by applying high-frequency energy of 200 volts and forming a film on a Si substrate maintained at room temperature under a self-bias condition of -150 V for 150 minutes. Next, methane with oxygen added was introduced from the nozzle at a flow rate of 50 SCCM of oxygen and 1005 CCH of methane, and the pressure was reduced to 0.015 to
rr, high-frequency energy of 100 W was applied to methane, and the surface to be formed was maintained at 150° C. under a self-bias condition of −200 V to form a film for 150 minutes to form a second layer. Then, 80SC of oxygen was applied to the second layer from a nozzle.
CM, methane to which oxygen was added was introduced at a flow rate of 1005 CCH, the reaction system was maintained at 0°015 torr, and 200 W of high frequency energy was applied to the methane.
A third layer was obtained by forming a film for 60 minutes while keeping the surface to be formed at room temperature under the condition of a self-bias of -280 cm. These 3
When the Vickers hardness of the two layers was measured, the first layer had a hardness of 2.
000Kg/mm2, second layer 3300Kg/mm2
The thickness of the third layer was 4000 Kg/mm2, and a carbon film having a surface hardness similar to that of diamond could be formed with good adhesion to the surface on which it was formed.

[Example 3] Hydrogen was added to the reaction system in which the substrate having the surface to be formed was placed.
CCM, hydrogen-added methane was introduced at a flow rate of 1005 CCH, the pressure was maintained at 0.03 torr, and 100 W of high frequency energy was applied to the methane.
Film formation was performed for 0 minutes to form the first layer. Next, on top of the first layer, the first
A second layer was formed under the same conditions as the second layer. Then, it was performed on the second layer under the same conditions as the first layer except that the flow rate of hydrogen was 803 CCM. As a result, 2400K
g/mm2.3400 Kg/mm", 4200 Kg
/mm2, the first layer has a vinyl hardness of
A carbon film consisting of a third layer and a third layer could be formed. The surface hardness of this carbon film is 420Q Kg/mm”
It has a hardness similar to that of diamond, and has excellent wear resistance, high thermal conductivity, and high smoothness.

In this example, the hardness of the carbon film was increased by increasing only the flow rate of hydrogen, but the same effect can be obtained by decreasing the flow rate of methane.

Further, in this example, each carbon film layer was formed using one reaction chamber, but each layer may be formed in a different reaction chamber by connecting a plurality of reaction chambers.

[Example 4] Oxygen was added to the reaction system in which the substrate having the surface to be formed was placed.
CCM, methane to which oxygen was added was introduced at a flow rate of 1003 CCH, the pressure was maintained at 0.03 torr, and 100 W of high frequency energy was applied to the methane.
Film formation was performed for 0 minutes to form the first layer. Next, on top of the first layer, the first
A second layer was formed under the same conditions as the second layer. The test was then performed on the second layer under the same conditions as the first layer except that the oxygen flow rate was 805 CCM. As a result, 2200K
g/mm2.3100 Kg/mm2.4000Kg/
A carbon film consisting of a first layer, a second layer, and a third layer having a Vickers hardness of mm'' could be formed.

This carbon film has a surface hardness of 4000 Kg/mm2, which is similar to diamond, and has wear resistance, high thermal conductivity,
It had excellent high smoothness.

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

Further, in this example, each carbon film layer was formed using one reaction chamber, but each layer may be formed in a different reaction chamber by connecting a plurality of reaction chambers.

[Example 5] In this example, instead of stacking layers with different hardness on the surface to be formed, a carbon film whose hardness is continuously changed by continuously increasing the amount of hydrogen added is used. was formed.

First, film formation was started under the same conditions as for forming the first layer in Example 1, and then the amount of hydrogen added was changed from 0.5 to 11.
A carbon film was formed on the surface to be formed by increasing the rate of increase to 1005 CCH at a rate of increase of 0.05 CC/min. The formed carbon film has a weight of 4200 Kg/
It had a Vickers hardness of mm2 and was excellent in wear resistance, high thermal conductivity, and high smoothness.

In this embodiment, only the flow rate of hydrogen was continuously increased, but only the flow rate of methane may be continuously decreased, or hydrogen may be replaced with oxygen.

[Example 6] In this example, before forming a carbon film on the surface to be formed, the surface to be formed is placed in an atmosphere of oxygen atoms activated by ultraviolet light and ozone generated by ultraviolet light. After removing organic contaminants or foreign substances from the surface to be formed, a carbon film was formed.

Organic contaminants on the surface to be formed are the biggest cause of reducing the adhesion between the surface and the film formed thereon. The apparatus used in this example is shown in FIG.

FIG. 6 shows a combination of the reaction chamber (24) shown in FIG. 1 and a preliminary chamber (25) that creates an atmosphere of oxygen atoms activated by ultraviolet light and ozone generated by ultraviolet light. A gate valve (23) is provided between the reaction chamber (24) and the preliminary chamber (25). The preliminary chamber is equipped with a low-pressure water filter (185 nm, 254 nm) (21) and a shutter (22). In this preliminary chamber (25), active oxygen and ozone are generated by the following reaction, and these remove organic contaminants on the surface to be formed.

02 +h V (185nm) →0+00□+0→
03 03+ h v (254nm) −+ 0”+O□
03 +C, HI, 1Ok-+CO, COz, HzO
Di+Cl1H1llOk-+C0IC0□, HzO, that is, it decomposes and removes organic substances (C-H-Oi=) on the surface to be formed by the combined action of ultraviolet light energy, ozone generated by ultraviolet light, and activated oxygen atoms. be.

In carrying out the experiment, first, a substrate having a surface to be formed was placed in a preliminary chamber, and then a low-pressure mercury lamp was turned on to decompose and remove organic matter on the surface to be formed. This low-pressure mercury lamp may be lit in advance and the shutter (22) may be opened. After that, turn off the lamp (you may close the shutter) to reduce the pressure in the preliminary chamber, and when the pressure becomes the same as that in the reaction chamber, open the gate valve (23) installed between the reaction chamber and the substrate. Moved to room.

After such treatment, a carbon film was formed on the surface to be formed according to the method of Example, Example 2, Example 3, Example 4, or Example 5.

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, after removing contaminants such as organic substances, film formation can be carried out in a reaction chamber in a short time without exposure to the atmosphere.

Although the above examples limit the number of additives to one type, the effects of the present invention can be obtained even if a mixture of two or more types is added.

〔effect〕

As described above, the carbon or carbon-based coating produced by the method of the present invention has a hardness that can be produced by changing the amount of hydrogen or oxygen added and by self-biasing to an extent that does not damage the surface on which it is formed. Alternatively, a film containing carbon as the main component is formed, and films with gradually increasing hardness are laminated to form carbon or a film containing carbon as the main component with the desired hardness on the surface. It has a hardness similar to that of diamond and has excellent adhesion to the forming surface, making it extremely effective for electrical parts such as magnetic heads and magnetic disks where dissimilar materials rub against the surface. . In particular, the resulting carbon or carbon-based coating has a thermal conductivity of 2.5 W/cm deg or higher, typically 4.0 to 6
．． OW/cm deg and diamond 60W/cm
degree, it is possible to uniformly dissipate the heat generated by friction throughout the film, and it also has characteristics such as wear resistance, high thermal conductivity, and high smoothness unique to carbon films. Further, the method of the present invention can be applied to organic resins, glass, magnetic materials,
Since it can be implemented using metal, ceramic, semiconductor, etc. as the surface to be formed, its applications are immeasurable.

[Brief explanation of the drawing]

FIG. 1 shows an overview of the apparatus used in the present invention. FIG. 2 is a diagram showing self-bias with respect to the addition flow rate of hydrogen and oxygen. FIG. 3 is a diagram showing the relationship between addition flow rate and Vickers hardness. FIG. 4 and FIG. 5 are diagrams showing the relationship between the addition flow rate and the film thickness. FIG. 6 is a diagram showing the apparatus used in Example 4. ■...Doping system 6...Valve 7...Flowmeter 8...Reaction system 9...Nozzle 10...Microwave energy 11...First electrode 12...Second Electrode 13... High frequency power supply 14... Matching transformer 15... DC bias power supply 16... Exhaust system 17... Royal power adjustment valve 18... Turbo molecular pump 19... Rotary pump 20. ...Reaction space? Kaikarokasu flow rate (SCC~1) 2nd cause 3rd figure? Total daily curse flow rate (SCCM) Figure 4? Figure 5 NF3 Curse Flow Rate <5ccN1>

Claims (1)

[Claims] 1. Direct current or high frequency energy is applied between the first electrode and the second electrode provided in contact with the substrate having the surface to be formed, and the generated plasma generates hydrocarbon gas. In the method of forming a carbon film on the surface to be formed by causing a decomposition reaction with or in addition to this and an additive gas, hydrogen or oxygen is added when forming the carbon film. A method of forming a film containing the main component. 2. Direct current or high frequency energy is applied between the first electrode and the second electrode provided in contact with the substrate having the surface to be formed, and the generated plasma generates hydrocarbon gas or in addition to this. In the method of forming a carbon film on the above-mentioned surface to be formed by causing a decomposition reaction with an additive gas, carbon or carbon is formed as a main component by changing the amount of hydrogen or oxygen added when forming the carbon film. A method for forming carbon or a film containing carbon as a main component, characterized by increasing the hardness of the film from the surface on which it is formed toward the surface of the carbon film.