JPH0768077B2 - Gas phase synthesis of diamond by high frequency plasma - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention decomposes and excites a carbon compound in high-frequency plasma to form a substrate surface on a water-cooled support placed on the tail flame of the high-frequency plasma. The present invention relates to a method for depositing diamond.

[Conventional technology]

In general, for example, a high-frequency thermal plasma CVD apparatus shown in a schematic sectional view in FIG. 1 is known as an apparatus used in a method of vapor phase synthesizing diamond by using high-frequency plasma.

This apparatus consists of a plasma generation torch A and a diamond precipitation chamber B. First, Ar and H ₂ are introduced into the quartz tube 2 as the plasma generation gas from the gas introduction ports 1a and 1b, respectively, while the high frequency coil is used. A high frequency is applied to 3 to generate a high frequency plasma 6, and in this state, a gas inlet
A carbon compound such as CH ₄ is introduced from 1c, decomposed and excited in the high-frequency plasma 6, and diamond is applied to the surface of the substrate 4 on the water-cooled support 5 placed in the tail flame part of the high-frequency plasma. Is deposited.

[Problems to be solved by the invention]

However, in the above conventional method, the surface temperature of the substrate is controlled to a temperature within the range of 700 to 1000 ° C. for the purpose of suppressing the precipitation of graphite and amorphous carbon on the substrate. However, as described above, the substrate is constantly irradiated with ultra-high temperature plasma, so even if the support table on which it is placed is water-cooled, its surface temperature gradually rises and a long-time continuous reaction occurs. Then, the surface temperature of the substrate deviates from the temperature range suitable for the synthesis of diamond to a higher one, and there is a problem that graphite and amorphous carbon will eventually precipitate, so the synthesis reaction time is at most The limit is 20 minutes, and it is the current situation that the synthesis reaction time cannot be increased to increase the thickness of the diamond layer or increase the grain size thereof.

[Means for solving problems]

This invention has been made to solve the problems of the above-mentioned conventional vapor phase synthesis method of diamond by high frequency plasma, in which the carbon compound is decomposed and excited in the high frequency plasma,
When the diamond is deposited on the surface of the substrate on the water cooling support placed on the tail flame part of the high frequency plasma, the water cooling support is made movable, and a plurality of substrates are arranged on the water cooling support to support the water cooling support. The table is moved to a diamond deposition step by irradiation of high frequency plasma on each of the plurality of substrates placed on the water cooling support, and the inside of the water cooling support is cooled by being released from the irradiation of high frequency plasma. The cooling process is repeated alternately with water, which prevents the surface temperature of the substrate from being overheated by high-frequency plasma, and prevents the precipitation of graphite and amorphous carbon. It is characterized in that it can be made into a coarse grain.

〔Example〕

Next, the method of the present invention will be specifically described by way of Examples.

Example 1 The method 1 of the present invention was carried out using the high frequency thermal plasma CVD apparatus shown in the schematic sectional view of FIG.

The apparatus shown in FIG. 2 has a water cooling support 5 having a rectangular vertical cross-section, which is skewed to a horizontal rotation axis of the cooling water circulation, as compared with the conventional high frequency thermal plasma CVD apparatus shown in FIG. It has the same structure except that it is mounted in a circular shape and is rotatable, and mirror-polished Mo substrates 4 are installed on the upper and lower surfaces of the water-cooling support 5.

That is, using the apparatus shown in FIG. 2, first, Ar and H ₂ are supplied as A to plasma generation gas from the gas inlets 1a and 1b.
r: 40 / min and H ₂ : 10 / min respectively flow into the quartz tube 2, while the high frequency coil 3 applies a high frequency of 4 MHz and an output of 40 KW to generate a high frequency at atmospheric pressure. Plasma 6 is generated, and in this state, CH ₄ gas as a carbon compound is introduced at a rate of 0.8 / min from the gas introduction port 1c, decomposed and excited in the high frequency plasma, and every 30 seconds.
Mo substrate 4 placed on a water-cooled support 5 that rotates 180 °
The method 1 of the present invention was carried out by depositing diamonds alternately and repeatedly on the surface of, and carrying out this for 1 hour.

Example 2 High-frequency thermal plasma also shown in a schematic sectional view in FIG.
Using the CVD apparatus, the method 2 of the present invention was carried out under the same conditions as in Example 1.

That is, in the apparatus shown in FIG. 3, the water-cooling support 5 is reciprocally movable, and the two substrates 4 arranged symmetrically on the upper surface of the water-cooling support 5 are alternately irradiated with the high-frequency plasma 6. 2 is different from the device shown in FIG.

Example 3 The method 3 of the present invention was carried out using the high frequency thermal plasma CVD apparatus shown in the schematic sectional view of FIG.

The apparatus shown in FIG. 4 has a water-cooled support base 5 which is rotatable as compared to the conventional high-frequency thermal plasma CVD apparatus shown in FIG. It has the same structure except that the two substrates 4 are arranged at symmetrical positions and one of them is irradiated by the tail flame portion of the high frequency plasma 6.

That is, using the apparatus shown in FIG. 4, first, Ar and H ₂ are supplied as gas for plasma generation from the gas inlets 1a and 1b.
Ar: 20 / min and H ₂ : ₂ : min flow into the quartz tube 2 respectively, while the high frequency coil 3 has a frequency of 13.56MH.
z, output: High frequency of 2 KW is applied to generate high frequency plasma 6 at a pressure of 500 torr, and in this state CH ₄ gas as a carbon compound is introduced at a rate of 50 ml / min from the gas inlet 1c, Is decomposed and excited in the high-frequency plasma,
While maintaining the pressure inside the chamber B at 8 torr, it is an unpolished Mo placed on the water-cooled support 5 that rotates half a turn every 30 seconds.
Diamonds are deposited alternately and repeatedly on the surface of the substrate 4 to be manufactured, and this is carried out for 30 minutes.
Was carried out.

Comparative Example 1 Further, for the purpose of comparison, the conventional method 1 was performed under the same conditions as the method 1 of the present invention except that the apparatus shown in FIG. 1 was used and the substrate 4 was fixed.

Comparative Example 2 Similarly, the conventional method 2 was carried out using the apparatus shown in FIG. 1 under the same conditions as the method 3 of the present invention.

〔The invention's effect〕

Then, the resulting coating on the substrate surface is SEM,
Observation by X-ray diffraction and Raman spectroscopic analysis revealed that a uniform diamond film having a layer thickness of 23 μm was formed in each of Inventive Methods 1 and 2, and a particle diameter of approximately 30 μm in Inventive Method 3. While the diamond particles of the same size were formed, in the conventional methods 1 and 2, the particle size was 5 μm.
The graphite film covered the scattered diamond particles of about m.

As described above, according to the method of the present invention, even by vapor phase synthesis of diamond for a long period of time, it is possible to deposit diamond without depositing graphite and amorphous carbon, It is possible to obtain industrially useful effects such as thickening of the film and coarsening of the particles.

[Brief description of drawings]

FIG. 1 shows a high-frequency thermal plasma as an apparatus for implementing the conventional method.
FIG. 2, FIG. 3, FIG. 3 and FIG. 4 are schematic sectional views showing a high frequency thermal plasma CVD apparatus as an apparatus for carrying out the method of the present invention. 1 ... Gas inlet, 2 ... Quartz tube, 3 ... High frequency coil, 4 ... Substrate, 5 ... Water cooling support, 6 ... High frequency plasma, A ... Plasma generating torch, B ... Diamond deposition For chamber.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yuzo Osawa 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Metal Co., Ltd. Central Research Institute (72) Inventor Hiroaki Yamashita 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Metal Corporation Shikisha Central Research Institute (56) References Japanese Patent Publication Sho 62-21757 (JP, B2)

Claims (1)

[Claims] 1. A method of decomposing and exciting a carbon compound in high-frequency plasma to deposit diamond on a substrate surface on a water-cooled support placed in a tail flame portion of the high-frequency plasma, wherein the water-cooled support is moved. A high-frequency plasma, characterized in that a plurality of substrates are arranged on the water-cooled support base, the water-cooled support base is moved, and irradiation and cooling of high-frequency plasma are alternately and repeatedly applied to each of the plurality of substrates. Vapor phase synthesis of diamond by.