JPH01298165A - Manufacture of carbon film - Google Patents

Abstract

PURPOSE:To stably manufacture a carbon film at high film-forming speed over a long period by synchronizing the output of high-frequency waves or microwaves producing plasma decomposing a carbon compound-type gas with a positive or negative A.C. bias to be impressed on a substrate. CONSTITUTION:A carbon compound-type gas is introduced via a gas-introducing hole 3 into a high-frequency plasma CVD apparatus and discharged through a gas exhaust port 4. Further, high-frequency electric power is impressed from a high-frequency electric power source 2 on a high-frequency coil 1 to produce plasma. The above gas is decomposed by means of this high-frequency plasma, by which a carbon film of diamond, etc., is formed on a substrate 5 of the prescribed temp. held by a substrate holder 6 containing a heater 8. In the method of manufacturing the above carbon film, an A.C. bias is impressed from an A.C. bias electric power source 7 on the substrate 5, and further, the above high-frequency output is outputted while being synchronized with a positive or negative A.C. bias. By this method, a diamond-like carbon film or an isometric carbon hard carbon film can be formed at high film-forming speed, and this speed can be maintained even if film formation is continued for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to a method for manufacturing a hard carbon film such as diamond or i-carbon.

[Prior Art 1 Diamond has the highest hardness and thermal conductivity among substances, so its thin film applications are wide-ranging (and are being considered).

Conventionally, the manufacturing method of diamond-like carbon film is as follows.
For example, microwave plasma CVD method (Japanese Unexamined Patent Publication No. 59-3
098, etc.), ECR plasma CVD method (Japanese Unexamined Patent Application Publication No. 1986)
Manufacturing methods using plasma CVD methods, such as those disclosed in Japanese Patent Laid-open No. 0-103098 and Japanese Patent Application Laid-Open No. 60-103099, are known.

[Problem to be solved by the invention]

However, in these methods, the growth rate of diamond crystals is generally as slow as about 1 μffi/hour.

In order to accelerate the growth rate of the crystal, for example, a method of applying a DC bias onto the substrate, or a method of arranging an intermediate electrode between the plasma and the substrate and irradiating the substrate with charged particles can be carried out. If you do those methods,
The crystal growth rate at the beginning of film formation can be improved.

However, as the film continues to be formed and the film thickness increases, these methods lose their effectiveness. This is because, in the method of applying a DC bias, the film on the substrate becomes thicker as the film continues to be formed, and the film is a highly insulating film (such as a diamond-like carbon film). Further, in the method of arranging the intermediate electrode, as film formation continues, a highly insulating film is formed on the surface of the intermediate electrode.

The purpose of the present invention is to increase the growth rate of diamond crystals,
Another object of the present invention is to provide a method for producing a carbon film that can maintain a high film formation rate even if film formation is continued for a long time.

[Means for Solving the Problems] The present invention provides a method for producing a carbon film in which a carbon compound gas is decomposed by high-frequency plasma or microwave electron cyclotron resonance plasma to form a film on a substrate, including the steps of: The method of manufacturing a carbon film is characterized in that a bias is applied and the high frequency output or the microwave output is output in synchronization with the positive or negative of the alternating current bias.

In the method of the present invention, since a specific alternating current bias is applied to the substrate, the film formation speed is faster than that of the conventional plasma CVD method, and the film formation speed can be maintained even if the film formation continues for a long time. I can do it. Furthermore, no charge is accumulated on the substrate, and therefore problems such as dielectric breakdown of the film are less likely to occur.

Furthermore, in the method of the present invention, the high frequency output for generating plasma is output in synchronization with the positive or negative AC bias applied to the substrate, so the crystallinity in the film can be easily controlled. It is possible to obtain a film with high crystallinity or a film with low crystallinity.

Devices that can be used in the method of the present invention include devices that have means capable of generating plasma and means capable of applying a high frequency bias to the substrate.

The above means capable of generating plasma is a means capable of generating plasma capable of decomposing carbon compound gas, such as a device having a high frequency power source and a high frequency coil, or a device having a microwave power source, its waveguide, and an electromagnetic coil. etc.

Hereinafter, the method of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of a high frequency plasma CVD apparatus that can be used in the method of the present invention.

In this device, raw material gas is introduced through a gas inlet 3 and exhausted through a gas exhaust port 4.

The raw material gas is decomposed by a high frequency coil 1 connected to a high frequency power source 2. Further, the substrate 5 is placed on a substrate holder 6, heated by a heater 8, and applied with an AC bias by an AC bias power source 7.

In the device shown in Fig. 1, the high frequency output from the high frequency power supply 2 is generally as shown in Fig. 3 if the input power supply is 50Hz (if AC is 60Hz, it is l/
(This will be a mountain every 120 seconds).

FIG. 2 is a schematic diagram showing an example of an ECR plasma CVD apparatus that can be used in the method of the present invention.

Raw material gas is introduced through the gas inlet 3 and exhausted through the gas exhaust port 4. 9 is a microwave power supply, and microwaves are introduced through a waveguide 10, and an electromagnetic coil II generates an electron cyclotron plasma to decompose the raw material. The substrate 5 is fixed by a substrate holder 6, heated by a heater 8, and further applied with an AC bias by an AC bias power source 7.

Hereinafter, the method of outputting high frequency or microwave output in synchronization with the positive or negative AC bias according to the present invention will be described in detail.

FIGS. 4 and 5 are diagrams showing examples of the bias application method and high frequency or microwave output input method of the present invention. In the figure, an AC bias of 50 Hz is applied.

FIG. 4 shows an example in which an alternating current bias is applied to the base, and further adjustment is made so that high frequency output or microwave output is output only when the base bias is negative. By adjusting in this manner, the substrate receives the effect of ion irradiation, and a hard carbon film, generally called i-carphone, grows at a high growth rate.

FIG. 5 shows an example in which high frequency output or microwave output is adjusted to be output only when the substrate bias is positive. By adjusting in this manner, the substrate receives the effect of electron irradiation, and a highly crystalline, so-called diamond-like carbon film is deposited at a high growth rate. Moreover, even if the film thickness increases, the bias effect remains unchanged.

The term "diamond-like carbon film" as used herein refers to a film having properties similar to diamond, having a Vickers hardness of about 2000 kg/mm2 or higher and a high insulation value of about 1O10 Ωcm.

In addition, in the example of FIG. 4 and FIG. 5, the synchronization of the high frequency output or the microwave output and the bias was shown so that the peaks coincided completely, but
The method of the present invention is not limited to this, and the phase may be shifted to some extent. When the phases are shifted to some extent and synchronized, a film of a mixture of i-carbon and diamond-like carbon is obtained due to the effects of both ion irradiation and electron irradiation.

Although the above is an example in which the AC bias is 50 Hz, the method of the present invention is not particularly limited as long as the AC bias is 1 kHz or less. If the frequency is higher than 1 kHz, it becomes difficult to generate plasma only when the voltage is positive or negative, and problems such as self-biasing occurring and the substrate being charged only negatively may occur.

As the raw material gas (carbon compound gas) used in the present invention, for example, a hydrocarbon gas such as methane or ethane can be used, and a mixed gas with 82, Ar, He, etc. as a carrier gas can also be used.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Using the high frequency plasma CVD apparatus shown in FIG. 1, the AC bias and high frequency output to the substrate were applied in synchronization as shown in FIG. 4, and the method of the present invention was carried out under the following conditions. i
- The six substrates on which carbon was deposited were silicon substrates, and hydrogen gas and methane gas were applied at 100 SCCM and 2 SC, respectively.
CM was introduced, and the pressure inside the chamber was set to 20 Torr. The high frequency output was 500 W and the substrate was heated to 600°C. Further, the AC bias was set to Vp = 100V.

Note that the frequency of the high frequency is 13.56 MHz.

The carbon film obtained as above is a light brown transparent film with a smooth surface, and no crystallinity is observed by X-ray diffraction]-
It was a carbon film.

The Vickers hardness of the film was 6000 kg/mm2, and the film formation rate was 5 μm/hour.

Example 2 A diamond-like carbon film was formed by carrying out the method of the present invention under the same conditions as in Example 1, except that the high frequency output was applied in synchronization as shown in FIG.

Diamond crystals were confirmed by X-ray diffraction of the carbon film obtained as described above.

The diamond-like carbon film showed clearly euhedral crystals when observed using a scanning electron microscope.

The film formation rate was 4 μm/hour.

Example 3 Using the ECR plasma CVD apparatus shown in Fig. 2, the AC bias and microwave output to the substrate were applied in synchronization as shown in Fig. 4, and the method of the present invention was carried out under the following conditions. i-carbon was formed into a film.

The base is silicon, and hydrogen gas and methane gas are each +
00 SCCM and 20 SCCM were introduced, and the pressure inside the chamber was set to I x 10-2 Torr. The microwave output was 500 W and the substrate was heated to 600°C. Further, the AC bias was Vp = 100 V, the microwave frequency was 2.45 MHz, and the ta field was 875 Gauss at the microwave introduction window.

The carbon film obtained as described above was a light brown transparent film with a smooth surface, and was a 1-carbon film with no crystallinity observed by X-ray diffraction.

The Vickers hardness of the film was 6000 kg/mm2, and the film forming rate was 8 taps/hour.

Example 4 A diamond-like carbon film was formed by carrying out the method of the present invention under the same conditions as in Example 3, except that the AC bias to the substrate was applied synchronously as shown in FIG.

Diamond crystals were confirmed by X-ray diffraction of the carbon film obtained as described above.

The diamond-like carbon film was found to be smooth when observed using a scanning electron microscope. The deposition rate was 5)1111/hour.

Comparative Example 1 Film formation was carried out in the same manner as in Example 3 except that no high frequency bias was applied.

Diamond crystals were confirmed by X-ray diffraction of the carbon film obtained as described above.

However, when the film was observed under a scanning electron microscope, it was found that aggregates of diamond grains in the form of a diamond were deposited on the substrate in the form of a film. In addition, the precipitation rate was 1 μm/
It was late.

[Effects of the Invention] As explained above, the method of the present invention based on the plasma CVD method applies a specific AC bias to the substrate.
The carbon film is formed at a high speed, and this speed can be maintained even if the film formation continues for a long time. Furthermore, depending on the AC bias application conditions, an amorphous hard carbon film (i-carbon, etc.) and a highly crystalline carbon film (diamond-like carbon film) can be produced as required.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a high frequency plasma CVD apparatus that can be used in the method of the present invention. FIG. 2 is a schematic diagram showing an example of an ECR plasma CVD apparatus that can be used in the method of the present invention. FIG. 4 and FIG. 5 are diagrams showing an example of the bias application method in the method of the present invention. 1...High frequency coil 2...High frequency power supply 5...Base 6...Base holder 7...AC bias power supply 9...・Microwave power supply

Claims (1)

[Claims] A method for producing a carbon film, in which a carbon compound gas is decomposed by high-frequency plasma or microwave electron cyclotron resonance plasma to form a film on a substrate, comprising: applying an alternating current bias to the substrate; A method for producing a carbon film, characterized in that the high frequency output or the microwave output is output in synchronization with positive or negative AC bias.