JPH0449520B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] Regarding a method for vapor phase synthesis of diamond at a high growth rate, the purpose of this invention is to provide a method for growing a diamond film at high speed and as a uniform film with a smooth surface. Using a plasma torch, multiple thermal plasma jets are collided with each other, carbon-containing compounds are turned into plasma in the plasma jets, and this is rapidly cooled and irradiated onto the substrate to form a uniform, smooth surface on the substrate. The configuration is configured to produce a diamond film.

[Industrial application field]

The present invention relates to a method for vapor phase synthesis of diamond at a high growth rate.

[Conventional technology]

Diamond film has a thermal conductivity of 2000 W/mK, four times that of copper, and has excellent hardness and insulation properties, making it an ideal material for semiconductor heat sinks and circuit board materials.

It also has excellent translucency over a wide wavelength range,
Excellent as an optical material. Furthermore, diamond has a wide bandcap of 5.4eV and is a semiconductor with high carrier mobility, making it a high-temperature transistor.
It is also attracting attention as a high-performance device such as high-speed transistors. Conventionally, chemical vapor deposition (Chemical vapor deposition) has been used as a method for vapor phase synthesis of high quality diamonds.
Vapor Deposition, CVD method), but it has the disadvantage that the film forming speed is slow at several μm/h.

To synthesize diamond at high speed in the vapor phase,
Active species such as hydrogen atoms and hydrocarbon radicals must be supplied onto the substrate at a high density. Such a high radical concentration can be obtained by generating thermal plasma;
Due to its high temperature of over 5000°C, it cannot be directly supplied onto the substrate. There, the thermal plasma is rapidly cooled,
Freezing the high gas dissociation rate at high temperatures,
DC plasma jet CVD that supplies non-equilibrium plasma with high radical concentration even at low temperatures onto the substrate
The method involves rapidly cooling the thermal plasma by bombarding a water-cooled substrate with thermal plasma generated by DC arc discharge as a plasma jet, or by blowing cooling gas onto the plasma jet, thereby rapidly synthesizing diamond on the substrate. It is. Using this method, we were able to fabricate a diamond film at high speed. In the method of injecting one plasma jet, the diamond particles generated on the substrate grow selectively, and only some of the particles become larger in size, creating a film with a smooth and uniform surface. It was difficult.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a method for growing a diamond film at high speed and as a uniform film with a smooth surface.

[Means for solving problems]

The above-mentioned problem can be solved by using a plurality of plasma torches, colliding a plurality of thermal plasma jets with each other, and converting a carbon source into plasma in the plasma jets to form diamond. This problem can be solved by a phase synthesis method.

[Effect]

By colliding multiple thermal plasma jets with each other,
It is thought that a large number of fine diamond nuclei are generated by turning a carbon-containing compound into plasma in a plasma jet and rapidly cooling it. Therefore, unlike in the conventional method, only some diamond nuclei grow and the surface of the diamond film does not exhibit irregularities, and a smooth diamond film with excellent uniformity can be produced.

〔Example〕

FIG. 1 is a diagram showing the principle of an apparatus in which one thermal plasma CVD apparatus is further equipped with one thermal plasma jet generation torch.

1 is an anode, 2 is a cathode, 3 is a discharge gas or a discharge gas containing a source gas, 4 is a cooling gas or a cooling gas containing a source gas, 5 is an arc, 6 is a nozzle, 7
1 is a plasma jet, 8 is a vacuum chamber, 9 is a substrate holder, 10 is a substrate, and 11 is a diamond film.

FIG. 2 is an overall view of an apparatus for implementing the present invention.

12 is a first plasma torch, 13 is a second plasma torch, 14 and 15 are arc power sources for each torch, 16 and 17 are cooling water arrangements for each torch, 18 is a substrate manipulator, 19 is a torch manipulator, 20 21 is an exhaust system, 21 is a gas cylinder, 22 is a flow meter, 23 is a discharge gas supply pipe containing discharge gas or raw material gas, 24 is a raw material gas and/or cooling gas supply pipe, and 25 is a cooling gas ejection pipe.

A 5 cm square Si substrate 10 was set 100 mm below the torch 12, and after exhausting to 1 × 10 ^-z Torr with a rotary pump, discharge gas H ₂ was applied to the torch 12 at 50 SLM.
Supply raw material gas CH ₄ at 500SCCM and discharge power
3kW, system pressure 100Torr, and torch 13 has 20SLM of discharge gas _H2 and raw material gas.
100 SCCM was supplied, and the film was formed for 1 hour at a discharge power of 1 kW, a distance between the substrate and the torch of 35 mm, and an angle of 60° with the substrate surface. When this film was analyzed by X-ray diffraction and Raman spectroscopy, a film exhibiting a diamond peak was produced. FIG. 3 shows a diamond film produced using two plasma torches according to the present invention, the film thickness was 30 μm, and the film forming rate was 100 μm/hr. FIG. 4 shows a diamond film produced using only the plasma torch 12 in a comparative method. According to the present invention, diamond with a smooth and uniform surface could be produced at high speed.

In the above embodiment, hydrogen from the discharge gas supply pipe 23,
Although an example has been given in which methane is supplied to the plasma torches 12 and 13 from the raw material gas supply pipe 24, both hydrogen and methane may be supplied from the discharge gas supply pipe 23, or cooling gas H ₂ and methane may be supplied from the raw material gas supply pipe 24. can also be supplied. Furthermore, various modifications may be made, such as supplying discharge gas and raw material gas to only one plasma torch, and supplying only discharge gas to the other plasma torch. The key is to irradiate a plurality of plasma jets, turn the carbon source into plasma in the plasma, and form diamond on the substrate. Although it is preferable for one of the plurality of plasma jets to be perpendicular to the substrate from the viewpoint of growth rate, the angles of the plurality of plasma jets can be arbitrarily set to an optimal predetermined angle.

Among the plurality of plasma jets mentioned above, a DC plasma jet using DC arc discharge is preferred, but RF plasma jet using high frequency discharge, photo arc plasma jet using photo arc discharge using a laser beam, and micro discharge using micro discharge may also be used. It is also possible to use a combination of various plasmas, such as a wave plasma jet or a plasma jet using alternating current discharge. Although a reduced pressure atmosphere is preferred as the plasma generation atmosphere, atmospheric pressure or increased pressure can also be used for diamond production. Furthermore, it can be applied to the synthesis of diamond powder.

〔Effect of the invention〕

According to the present invention, a diamond film with a smooth and uniform surface can be formed at high speed using the DC plasma jet CVD method, and the range of application of coating can be greatly expanded. This will greatly advance the realization of diamond heat sinks and diamond circuit boards for semiconductor devices.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of thermal plasma jet CVD of the present invention, FIG. 2 is an overall diagram of an apparatus for implementing thermal plasma jet CVD of the present invention, and FIG.
The figure shows the structure of a diamond film crystal according to the present invention, and FIG. 4 shows the structure of a diamond film crystal obtained by a conventional method. 1...Anode, 2...Cathode, 3...Discharge gas or discharge gas containing source gas, 4...Cooling gas,
or cooling gas containing raw material gas, 5... arc,
6... Nozzle, 7... Plasma jet, 8...
Vacuum chamber, 9...substrate holder, 10...substrate, 11...diamond film, 12...first plasma torch, 13...second plasma torch,
14, 15... Arc power supply, 16, 17... Cooling water piping for torch, 18... Board manipulator,
19... Torch manipulator, 20... Exhaust system, 21... Gas cylinder, 22... Flow meter, 23
...discharge gas supply pipe, 24...raw material gas supply pipe,
25...Cooling gas ejection pipe.

Claims (1)

[Claims] 1. A diamond characterized in that a diamond is formed by using a plurality of plasma torches, colliding a plurality of thermal plasma jets with each other, and turning a carbon source into plasma in the plasma jets. vapor phase synthesis method. 2 Using multiple plasma torches, carbon compounds are turned into plasma, multiple thermal plasma jets are collided with each other, and the plasma jets are rapidly cooled and irradiated onto the substrate to form a uniform and smooth surface on the substrate. A method for vapor phase synthesis of a diamond film according to claim 1, characterized in that a diamond film is produced.