JPS63270393A - Method for synthesizing diamond - Google Patents

Abstract

PURPOSE:To form diamond on a substrate at a high synthetic rate with good productivity, by using water as a plasma stabilizing medium, introducing a carbon source into a water plasma jet generated by arc discharge and blowing the jet on the substrate. CONSTITUTION:High-pressure water 2 is introduced into an arc chamber 15 to form a cylindrical eddy water stream 5. Arc discharge is then generated between a cathode 1 and anode 7 on the central axis of the stream 5. Thereby water on the inside diameter surface of the cylindrical eddy water stream 5 is instantaneously evaporated and ionized to generate a thermal plasma of a high density. A carbon source 11 (e.g. methane) for synthesizing diamond is introduced into a plasma jet 10 jetted from the arc chamber 15 to activate the carbon source 11 with a high efficiency and form radicals and ions of a high density, which are then blown on a substrate 13 at an ultrahigh speed to deposit diamond 14 on the substrate 13. Thereby the aimed diamond is synthesized.

Description

[Detailed Description of the Invention] [Summary] By spraying highly active water plasma generated by arc discharge onto a substrate to synthesize diamond,
The diamond growth rate can be increased compared to conventional methods.

[Industrial application field]

The present invention relates to a method for vapor phase synthesis of diamond, and in particular to a method capable of synthesizing diamond at a high film forming rate, continuously, and in an atmospheric atmosphere.

[Conventional technology]

Conventionally, as a vapor phase synthesis method for high-quality crystalline diamond, the hot filament method (S, Matsus+oto et al.: Jp.
n, J, App1. Phys, Vol. 2, Ha
4 (1981) L183-I, 185), a microwave plasma CVD method that sends a mixed gas of methane and hydrogen under microwave discharge conditions (M, Kamo et al.: J, Cryst
, Growth 62 (1983) pp. 642-444)
, an electron beam irradiation CVD method in which electrons collide with the substrate surface on which diamond grows (A, Sawabe et al.: Appl.
, Phys., Lett.

Vol 46, tlh 2, (1985) 14
6-147) etc. (7) CVD method.

[Problem that the invention seeks to solve]

However, the above-mentioned methods have a serious drawback in that the film formation rate is low at 1 (DJ/h or less).Moreover, these methods require a reduced pressure H2 atmosphere, which poses problems in terms of cost and productivity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that solves the above-mentioned problems, has a high film forming rate, and is capable of synthesizing diamond under atmospheric conditions.

[Means for solving problems]

The means for solving the above problems provided by the present invention is to introduce a carbon source for diamond synthesis into a water plasma jet generated by arc discharge, using water as a plasma stabilizing medium, and to A method for synthesizing diamond characterized by spraying a jet onto a substrate to deposit diamond on the substrate.

As a carbon source for diamond precipitation, ethylene or carbon powder can be used.

The atmosphere for diamond synthesis is normal pressure or reduced pressure (
Atmospheric pressure (about 30 torr is preferred) or hydrogen can be used.

[For production]

The water plasma formed by arc discharge is a high-density thermal plasma, and the carbon source introduced into the thermal plasma is activated with high efficiency and becomes high-density radicals and ions, which collide with the substrate at ultra-high speed. , produce diamonds. Hydrogen and oxygen ions and atoms, which are the main components of plasma, quickly remove graphite and amorphous carbon, which are generated at the same time as diamond, so that only diamond grows. In this way, by using extremely highly active thermal plasma, radicals can be generated at a much higher density than in conventional CVD, so diamond can be synthesized at a high rate.

In addition, water plasma becomes water vapor after being cooled, so it is highly safe and can be operated in the atmosphere.

〔Example〕

FIG. 1 shows a water plasma CV for carrying out the method of the present invention.
The structure of the diamond vapor phase synthesis apparatus according to D is shown. 1 is a cathode, 2 is a water inlet, 3 is a water outlet, 4 is an insulator, 5 is a cylindrical turbid water flow, 6 is an arc column, 7 is a rotating anode, and 8 is a cooling device. water, 9
is an arc power source, 10 is a plasma jet, 11 is a raw material,
12 is a raw material supply nozzle, 13 is a substrate, 14 is a diamond film, and 15 is an arc chamber.

The high-pressure water introduced into the arc chamber 15 forms a cylindrical turbid water flow 5 in the chamber, and when an arc discharge is caused between the cathode 1 and the anode 7 on the central axis, the water on the inner diameter surface of the cylindrical vortex water flow is It evaporates and ionizes instantly, creating a high-density thermal plasma. When raw materials such as methane are supplied into the plasma jet 10 injected from the arc chamber,
This raw material is activated with high efficiency and becomes a high density of radicals and ions, which collide at ultra-high speed with a substrate generally kept at a temperature of 600 to 1000 degrees Celsius, producing diamond.

■-Using a device with the configuration shown in Figure 1 above, turbid water flow inner diameter 2, arc length 30n, current 100A, voltage 80V, water supply pressure 12
Water plasma was generated under the condition of kg/c+4, and C1 was used as the raw material for 1. A 30 x 30 m silicon substrate was introduced into the plasma at a flow rate of O1/win, fixed to a water-cooled copper substrate holder, and the substrate was brought close to the plasma outlet until the substrate temperature reached 900°C, and film formation was performed for 1 hour. .

Analysis of the produced film revealed that it was colorless and transparent polycrystalline diamond with a thickness of 30(0). Additionally, a small amount of silicon carbide was detected at the diamond-silicon interface.

■-1 Under the same conditions as above, carbon black with an average particle size of 1(0) was supplied into the plasma at a rate of 0.1 g/min, and a film was formed in the same manner. A brown transparent film was obtained.Only diamond was detected by X-ray diffraction.

〔Effect of the invention〕

According to the present invention, by using highly active water plasma, the growth rate of diamond can be significantly increased compared to conventional methods, and improvements in cost and productivity can be achieved, such as by being able to utilize the atmospheric atmosphere. .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the state of diamond synthesis by water plasma CVD according to an embodiment of the present invention. 1...Negative, 2...Water inlet, 3
...Water outlet, 5...Cylindrical turbid water flow,
6... Arc column, 7... Rotating anode, 8
...Cooling water, 9...Arc power supply,
10... Plasma jet, 11... Raw material, 1
2... Raw material supply nozzle, 13... Substrate, 14...
...Diamond film, 15...Arc chamber. Diamond vapor phase synthesis by water zolazma CVD 11...
・Raw material 13...Substrate 14°゛°diamond film 15°・Arc chamberer

Claims (1)

[Claims] 1. Using water as a plasma stabilizing medium, a carbon source for diamond synthesis is introduced into a water plasma jet generated by arc discharge, and the plasma jet is blown onto a substrate to form a carbon source on the substrate. A diamond synthesis method characterized by precipitating diamond. 2. The method according to claim 1, wherein the carbon source for diamond precipitation is a gas, liquid, powder, or carbon powder containing carbon atoms in the molecule. 3. The method according to claim 1 or 2, in which atmospheric air or hydrogen at normal pressure or reduced pressure is used as the atmosphere for diamond synthesis.