JPH0814024B2 - High-pressure phase boron nitride vapor phase synthesis method - Google Patents

Description

Detailed Description [Overview] A method for continuously synthesizing high-pressure phase boron nitride (BN) by a vapor-phase synthesis method, and a method for vapor-phase synthesizing a high-quality high-pressure BN film at a high deposition rate For the purpose of providing, a raw material gas containing boron atoms and nitrogen atoms as gas constituents is turned into thermal plasma by arc discharge by inductive coupling of microwaves, and the obtained thermal plasma is irradiated onto the substrate as a plasma jet. It consists of vapor-phase growth of high-pressure phase boron nitride on a substrate by quenching.

[Industrial applications]

The present invention relates to high pressure phase boron nitride (BN) [cubic BN (c-B
N) and wurtzite-type BN (w-BN)], and more specifically to a method for continuously vapor-synthesizing high-pressure phase BN at a high film formation rate.

The high-pressure phase BN has a thermal conductivity and hardness comparable to that of diamond, and is superior in heat resistance to diamond. Therefore, if the high-pressure phase BN can be synthesized in a thin film, it can be used as a substrate for high-density mounting of semiconductor devices, heat sinks, and various It is expected to be used in a wide range of fields as a high hardness coating film for tools.

[Conventional technology]

Conventionally, IBD method (ionization vapor deposition), IVD method (ion vapor deposition combined method) HCD-ARE method (hollow cathode activated chemical vapor deposition), etc. are known as vapor phase synthesis methods for high-pressure phase BN. According to the method, the obtained high-pressure phase BN contains a low-pressure phase BN (h-BN) having a graphite structure and an amorphous component, and the film-forming rate is very slow at 1 μm / h or less,
It was an insufficient industrial process in terms of quality, cost and productivity.

[Problems to be solved by the invention]

As described above, when the high-pressure phase BN is synthesized by the conventional method, there is a problem that the obtained boron nitride is not sufficient in quality and the film forming rate is very slow.

Therefore, it is an object of the present invention to provide a method for vapor phase synthesizing a high-quality high-pressure phase BN film at a high film forming rate while eliminating the above-mentioned problems of the prior art.

[Means for solving problems]

According to the invention, the problem is that the raw material gas containing a boron atom and a nitrogen atom as gas constituents is converted into thermal plasma by arc discharge by inductive coupling of microwaves,
It is solved by a vapor phase synthesis method of high pressure phase boron nitride characterized in that high pressure phase boron nitride is vapor-deposited on the substrate by irradiating the obtained thermal plasma as a plasma jet on the substrate and quenching. .

Hereinafter, the present invention will be specifically described with reference to the accompanying drawings.

FIG. 1 is a view for explaining an example of an apparatus for vapor phase synthesis of high pressure phase BN according to the present invention.

In FIG. 1, 1 is a magnetron having an oscillation frequency of, for example, 2,45 GHz, and the microwave generated from this magnetron 1 is a general rectangular waveguide 2 and a coaxial waveguide.
The single electrode 8 passes through 15 and serves as a receiving antenna, and an extremely high electric field is generated at its tip. As a single electrode, for example, Y ₂
O ₃ -W, graphite, or the like can be used La ₂ O ₃ -W. The waveguides 2 and 15 can be made of brass, for example.

On the other hand, the raw material gas is introduced into the quartz tube 6 through the gas introduction port 3 from the gas introduction pipe 5 made of, for example, a quartz tube or fluororesin at atmospheric pressure or higher. This raw material gas is a raw material of BN, such as boron hydride such as B ₂ H ₆ , boron halide such as BCl ₃ , B ₂ (C
H ₃ ) ₆ etc. containing a boron atom-containing gas such as an organic boron compound and NH ₃ or N ₂ containing a nitrogen atom-containing gas,
Further, preferably, a gas for enhancing reactivity and H ₂ are contained, and as a gas for stabilizing plasma, Ar, He, etc. are contained. There is no limitation on each component in the raw material gas, but the following structures (volume%) are generally preferable.

Gas containing B atom 0.01 to 10% Gas containing N atom 0.01 to 10% H ₂ 20 to 100% Ar or He 0 to 80% The above-mentioned raw material gas is introduced from the gas introduction port 3 through the gas introduction pipe 5. The tip of the single electrode 5 is induction-heated to be highly activated high-temperature thermal plasma. The raw material gas flow is jetted from the nozzle 16 as the plasma jet 9 due to the rapid thermal expansion at this time. In addition, gas introduction pipe 5
At the tip of the single electrode 8 as shown in FIG.
Are fixed by the electrode support 7.

In the plasma jet 6 injected from the nozzle 16, the BN raw material gas in the raw material gas is decomposed and activated at high density, and when this collides with the substrate 10 at a temperature of 500 to 1200 ° C., for example,
Due to the rapid cooling effect of the thermal plasma, a large amount of BN source gas is highly activated in a non-equilibrium state, and a high-pressure phase is formed on the substrate 10 at a high film rate.
BN is vapor-phase synthesized. The substrate 10 is not particularly limited and is selected according to the intended product. For example, in the case of a semiconductor element, Si, Al ₂ O ₃ or the like is used. The substrate 10 is placed on the water-cooled substrate holder 11 in which the cooling water 14 provided in the chamber 12 is circulated, and the exhaust gas is exhausted from the exhaust system.

[Action]

As described above, according to the present invention, a large amount of the source gas containing B and N highly activated in the non-equilibrium state is supplied as a plasma jet onto the substrate, so that the high-quality high-pressure phase BN
It is possible to perform vapor phase synthesis at a high film forming rate.

Examples Examples of the present invention will be described below, but it goes without saying that the technical scope of the present invention is not limited to the examples.

2% Y ₂ O ₃ -W with a diameter of 3 mm and a length of 20 mm is used as a single electrode,
A microwave of 2.45 GHz and 2 KW was put into a microwave plasma torch attached to a waveguide having a cross section of 96 × 37 mm.
This _{Ar6 / min, H 2 3 /} min, B 2 Ho0.3 / min and NH ₃ 0.
A source gas of 5 / min was introduced. This source gas generated a plasma jet heated by microwaves around the single electrode. Chamber pressure is 200 Tor
r, 40 mm away from the nozzle, place a Si wafer of size 30 × 30 mm and a thickness of 0.5 mm on the water-cooled substrate holder, and control the cooling water flow so that the temperature of the Si wafer is 600 ° C, and BN for 1 hour. Was synthesized.

The produced film was a colorless film having a thickness of 30 μm, and when examined by X-ray diffraction and infrared spectroscopy, only the peak of c-BN was detected. Also, when the Vickers hardness was examined, it showed a value of 4000 to 5000 at a load of 500 g and a thermal conductivity of about 800.

〔The invention's effect〕

According to the present invention, by using a microwave plasma jet with high activity, there is almost no low-pressure phase BN as compared with the conventional method, and a high-quality high-pressure phase BN film having high thermal conductivity and hardness can be formed into a high film. Vapor deposition on a substrate at a rate,
Improvements in quality, cost and productivity have been achieved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an apparatus for vapor phase synthesis of high pressure phase BN according to the present invention. In FIG. 1, 1 ... Magnetron, 2 ... Rectangular waveguide, 3 ... Gas inlet, 4 ... Quartz tube, 5 ... Gas inlet pipe, 6 ... Quartz tube, 7 ... Electrode support Material, 8 ... Single electrode, 9 ... Plasma jet, 10 ... Substrate, 11 ... Water-cooled substrate holder, 12 ... Chamber, 13 ... Exhaust port, 14 ...
Cooling water, 15 ... Coaxial waveguide, 16 ... Nozzle.

Claims (3)

[Claims] 1. A raw material gas containing boron atoms and nitrogen atoms as gas constituents is turned into thermal plasma by arc discharge by inductive coupling of microwaves, and the resulting thermal plasma is irradiated onto a substrate as a plasma jet for rapid cooling. A vapor-phase synthesis method of high-pressure phase boron nitride, characterized in that high-pressure phase boron nitride is grown on the substrate by vapor phase growth. 2. The raw material gas is a boron hydride, a halide and / or an organic boron compound as a boron atom-containing gas, and NH ₃ and / or N is a nitrogen atom-containing gas.
_{2. A method according} to claim 1, which contains ₂ and further contains H ₂ as the gas for increasing the reactivity and Ar and / or He for stabilizing the plasma. 3. The method according to claim 1, wherein the temperature of the substrate is 500 to 1200 ° C.