JPH01298097A - Production of diamondlike carbon film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a diamond-like carbon film.

[Prior Art] Diamond has the highest hardness, thermal conductivity, etc. of all substances, and therefore its thin film applications are being widely studied.

Conventionally, the manufacturing method of diamond-like carbon film is as follows.
For example, the hot filament CVD method (Japanese Patent Application Laid-Open No. 58-911
Manufacturing methods using CVD methods such as the microwave plasma CVD method (Japanese Patent Publication No. 61-3320, etc.) are known.

In addition, as another method for producing a diamond-like carbon film, a sputtering method by sputtering a graphite target (Japanese Patent Publication No. 52-42159, Japanese Patent Application Laid-open No. 61-61
Publication No. 98, etc.).

[Problems to be Solved by the Invention] The above CVD method generally requires the substrate temperature to be as high as about 800°C. Therefore, the range of applications of the obtained diamond-like carbon film was narrow.

On the other hand, the sputtering method allows film formation even when the substrate temperature is relatively low, but the film formation rate is slow and there is a strong tendency for gases such as hydrogen to remain as impurities in the resulting film, resulting in poor crystallinity. There were disadvantages such as low

An object of the present invention is to provide a method for producing a diamond-like carbon film that can be formed even when the substrate temperature is relatively low, has a fast film formation rate, contains few impurities, and has good crystallinity. It's about doing.

[Means to solve the problem]

The present invention has a gas pressure of 5 x 1O - 5 x 1O-ITor.
A method for producing a diamond carbon film, which comprises sputtering a graphite cathode in a magnetic field with a gas containing one or more selected from hydrogen gas and rare gas within the range of r, and applying a high frequency bias to the substrate. It is.

The "diamond-like carbon film" referred to herein is a film having properties similar to diamond, having a Vickers hardness of about 2000 kg/mm2 and high insulation properties of about 1010 ΩCm.

In the manufacturing method of the present invention, an appropriate high frequency bias is applied to the substrate, so that the surface of the substrate is activated and impurities such as weakly bonded amorphous phase and carbon containing double bonds and hydrogen in the film are removed. etc. are removed, and the crystallinity of the resulting film is improved.

In addition, in the conventional sputtering method, carbon-carbon bonds are formed on the substrate only by the energy of sputtered carbon atoms or molecules, so the resulting film has poor crystallinity and does not contain double bonds. However, there was not enough energy provided to remove carbon and other substances.

In the present invention, the application of high frequency bias to the substrate is 1
The application may be performed using a high frequency of approximately 00 kHz to IGHz, and generally a normal high frequency power source of 13.56 MHz may be used.

The output of the high frequency bias is applied so that the self-bias voltage of the substrate generated by applying the high frequency bias is preferably 20 to 250 V, more preferably 50 to 200 V. If the voltage is lower than 20V, the effect of the present invention due to the application of high frequency bias may not be recognized, and if it is higher than 250V, the substrate temperature will rise during film formation and become high temperature. Because I put it away,
The purpose of the present invention, which is to obtain a good film while having the advantage of the sputtering method (capable of forming a film even at a relatively low substrate temperature), may not be achieved, and the film formation rate becomes slow.

The sputtering gas used in the method of the present invention includes hydrogen gas or a rare gas (He, Ar, Ne, etc.) alone or in combination.
This gas is a mixture of more than one species. By mixing the above-mentioned rare gas, it is possible to stabilize the discharge and increase the film formation rate.

In addition, the preferable value for the gas pressure in the reaction chamber in terms of stabilizing the discharge and obtaining high-density plasma varies depending on the distance between targets, magnetic field strength, etc.
The range of O= to 5 x 10-' Torr is desirable, and the range of I x 10' to 5 x 10-2 Torr is more preferable.

The strength of the magnetic field in the method of the present invention is 300 to 1000
A diameter of Oersted is desirable, and a range of 400 to 600 Oersted is more desirable.

The substrate temperature in the method of the present invention is 8
It is not necessary to set the temperature to a high temperature of about 00°C, but it may be about 200 to 400°C.

Apparatus that can be used in the method of the present invention includes means that can reduce the pressure in the reaction chamber and perform sputtering (magnets, DC power supplies, etc.), and means that can apply high frequency bias to the substrate (high frequency power supplies, etc.). ).

FIG. 1 is a schematic diagram showing an example of a facing sputtering apparatus that can be used in the method of the present invention.

In the figure, 1 is a chamber, 2 is a graphite target,
3 is a DC power source, 4 is a substrate, 5 is a substrate holder, 6 is a high frequency power source, 7 is a gas inlet, 8 is a gas exhaust port, 9 is a target holder with a built-in permanent magnet, and the magnetic field generated by the permanent magnet is The voltage is applied in the direction of the arrow in the figure.

In this device, when the sputtering gas introduced from the gas introduction lower is dissociated by a discharge current and turned into plasma,
The graphite target 2 is sputtered by the plasma, and a high frequency bias is applied by the high frequency power source 6. Then, a diamond film is formed on the substrate 4 on the substrate holder 5. Note that the inside of the chamber is evacuated through an exhaust port 8 by an exhaust system (not shown), and the pressure is adjusted to a predetermined pressure.

Typical discharge characteristics (relationship between discharge current and target voltage) in the above device are shown in FIG.

Note that the apparatus for carrying out the method of the present invention is not limited to the above-mentioned apparatus. For example, in the above-mentioned apparatus, two targets are used, but one or three or more targets may be used. Further, although a permanent magnet is used as the magnet, an electromagnet may also be used.

〔Example〕

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

Example 1 Using the facing sputtering apparatus shown in FIG. 1, the method for manufacturing a diamond-like carbon film of the present invention was carried out under the following conditions.

A silicon substrate was used as the base 4 and heated to 200° C. using a heater (not shown). Hydrogen gas was introduced as sputtering gas at 50 SCCM, and the pressure inside the chamber was reduced to 2.
X 1O-3 Torr. The magnetic field strength was 500 oersted, the target voltage was lkV, and the discharge current was 0.5
I gave it an A. A high-frequency bias was applied to the substrate 4 so that the self-bias was 5QV. At this time, the high frequency output was 20W. In addition, the frequency of the high frequency is 13.5
The frequency was set to 6 MHz.

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

The diamond-like carbon film has a Vickers hardness of 6000.
The film had a hardness of kg/mm2 and was smooth according to scanning electron microscopy. Also, according to IR measurement, C-H
Absorption was confirmed, but it was weak. The film formation rate was 4 coats/hour.

Example 2 Hydrogen gas and argon gas were introduced as sputtering gases at 25 SCCM each, and the pressure inside the chamber was set to 2
Film formation was performed in the same manner as in Example 1, except that the temperature was 10-3 Torr, the target voltage was 900 V, and the discharge current was 0.5 A.

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

The diamond-like carbon film has a Vickers hardness of 6000.
The film had a hardness of kg/mm2 and was smooth when observed using a scanning electron beam microscope. Further, according to IR measurement, almost no H was observed. The film formation rate is 6) + 111/
It was time.

Example 3 Adjust the exhaust valve (not shown) to reduce the pressure to 5×1O-3T
The film was formed in the same manner as in Example 2 except that the target voltage was 700 V and the discharge current was 0.5 A.

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

The diamond-like carbon film has a Vickers hardness of 5800.
The film had a hardness of kg/mm2 and was smooth according to scanning electron microscopy. Further, according to IR measurements, almost no H was observed. The film formation rate is 4μffi/
It was time.

Example 4 Film formation was performed in the same manner as in Example 2, except that the high frequency bias was adjusted and applied so that the self-bias was 100 V.

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

The diamond-like carbon film has a Vickers hardness of 9000
The film was hard, weighing 7 mm2, and was smooth when observed using a scanning electron microscope. Further, according to IR measurement, almost no H was observed. The film formation rate was 4 in/hour.

Comparative Example 1 Film formation was performed in the same manner as in Example 2, except that the exhaust valve (not shown) was adjusted to set the pressure to I Torr. At that time, the discharge was unstable and localized discharge occurred on the graphite target.

At this time, only soot deposits were obtained on the substrate.

Comparative Example 2 Adjust the exhaust valve (not shown) to reduce the pressure to I×10”T
Film formation was performed in the same manner as in Example 2, except that orr was used. At that time, the discharge was weak and a sufficient discharge current could not be obtained.

At this time, almost no precipitates were observed on the substrate.

Comparative Example 3 Film formation was carried out in the same manner as in Example 2 except that no high frequency bias was applied.

No diamond crystals were observed in X-ray diffraction of the carbon film obtained as described above.

The Vickers hardness of the carbon film is 3000 kg/mm2
A strong absorption of C-H was observed in the IR measurement.

Comparative Example 4 [Effects of the Invention] As explained above, the method of the present invention based on the sputtering method sputters a graphite cathode in a magnetic field with a sputtering gas at an appropriate gas pressure, and also applies a high frequency bias to the substrate. Since the application is applied, film formation is possible even when the substrate temperature is relatively low, and a diamond-like carbon film with high film formation rate, less contamination of impurities, and good crystallinity can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus that can be used in the method of the present invention, and FIG. 2 is a diagram showing typical discharge characteristics in a facing sputtering apparatus. 1... Chamber

Claims (1)

[Claims] Gas pressure 5×10^-^4 to 5×10^-^1 Torr
A method for producing a diamond-like carbon film, which comprises sputtering a graphite cathode in a magnetic field with a gas containing one or more selected from hydrogen gas and rare gases within the range of 1 to 2, and applying a high frequency bias to the substrate. .