JPH0818905B2 - Diamond synthesizing method and synthesizing apparatus - Google Patents

Description

The present invention relates to a diamond synthesizing method and a synthesizing apparatus by a chemical vapor deposition method.

[Conventional Technology and Its Problems] In recent years, diamond synthesis technology has been significantly developed.

So far, for example, chemical vapor deposition (CVD
Method), ion beam method, chemical transport method, and other various synthesis techniques have been known.

In particular, a method of forming a diamond thin film by a chemical vapor deposition method at a low temperature has recently attracted attention because of its easy continuous operation and industrial advantage.

On the other hand, in the industrialization of this CVD method, how to activate the mixed gas is an important issue. The way to do this is to use a thermal CV that brings the mixed gas into the activated state by passing it near the red-hot filament.
D method, high-frequency plasma CVD method that applies high frequency to the introduction part of the mixed gas and forms plasma by the high frequency to bring the mixed gas to an activated state, introduces microwaves to the gas introduction part, and uses microwaves there A microwave plasma CVD method is known in which a mixed gas is activated by forming plasma.

Among these, especially the microwave plasma CVD method,
It is highly promising because it has excellent reproducibility of the activated state and there are no consumable parts.

However, in the conventional microwave plasma CVD method, the microwave oscillated from one microwave oscillator is directly introduced into the plasma generator (see Japanese Patent Laid-Open No. 59-91100). In order to manufacture a large amount of the same at the same time, a large number of devices including a microwave oscillator and a plasma generator were required. Therefore, there is a problem that the production efficiency is low and it is industrially disadvantageous.

[Object of the Invention] An object of the present invention is to solve the above problems, to provide a mass-produced diamond thin film by a microwave plasma CVD method, and to provide an industrially advantageous method for producing diamond. To provide a manufacturing apparatus suitable for carrying out the method.

[Means for Achieving the Object] The outline of the first invention for achieving the object is as follows.
In a method of synthesizing diamond, a plasma obtained from a hydrogen gas and a carbon source gas by microwave irradiation in a plasma generator is introduced into a substrate surface to deposit diamond on the substrate surface. The microwave oscillated from the wave oscillator is branched into a plurality of beams so that the branched microwaves have the same intensity, and the branched microwaves are guided to a plurality of plasma generators with the same load. A method of synthesizing diamond, which is characterized by a second aspect of the present invention, in which a microwave oscillator that oscillates a microwave and a microwave oscillated from the microwave oscillator have the same intensity in each of the branched microwaves. And a substrate for diamond deposition that is connected to this branching waveguide And a plurality of plasma generators having the same load.

The synthesizing method according to the present invention will be described together with the diamond synthesizing apparatus which is an example of the second invention.

As shown in FIG. 1 (a), this diamond synthesizing apparatus comprises one microwave oscillator 1 and one branch waveguide 2
And two plasma generators 3.

The microwave oscillator 1 has a microwave band (frequency 10
It has an oscillation function at 00 MHz to 100 GHz, and specific examples thereof include conventionally known microwave tubes such as a velocity modulation tube, a klystron, and a magnetron.

In the present invention, of the microwaves, the ISM frequency band can be preferably used.

The branching waveguide 2 shown in FIG. 1 (a) equally divides the microwave oscillated by the microwave oscillator 1 into two directions so that the respective branched microwaves have the same intensity,
It is formed so that each of the branched microwaves in two directions is guided to each of the plasma generators 3 having the same load. In this example, the mayro wave oscillated from the microwave oscillator 1 is shown as a bidirectional branching waveguide that uniformly branches in two directions. However, the unidirectional microwaves are the same for each of the branched microwaves. When branching in three or more directions so as to have high strength, for example, a T-branch tube, an E-corner conversion waveguide
It is also possible to use a trifurcated pipe or a combination thereof.

In addition, the combination of the branch waveguide, microwave
The branched microwaves can be branched so that the microwaves have the same intensity, but can also be branched to have a desired ratio of intensity.

In the present invention, the microwaves branched by the branching waveguide 2 in a plurality of directions so that the respective branched microwaves have the same intensity are connected to the branching waveguide 2 and are connected to the plurality of plasmas of the same load. The mixed gas of the hydrogen gas and the carbon source gas supplied to the plasma generators 3 of the same load and supplied to each of the plasma generators 3 with the same load is irradiated with microwaves having a certain intensity to form plasma, thereby forming the plasma. Is activated.

As shown in FIG. 1B, the plasma generator 3 of the same load supplies a gas supply device 5 for supplying a mixed gas of hydrogen gas and a carbon source gas to the reaction chamber 4, and a reaction gas after use. The reaction chamber 4 has an exhaust device 6 for discharging the reaction gas to the outside, and the reaction chamber 4 has a built-in substrate 7 for depositing diamond on its surface. The substrate 7 is used after being heated by, for example, a heating furnace, if necessary.

The substrate 7 is not particularly limited, and for example, a conventionally used substrate such as glass, silicon, or metal can be used.

Further, the supply amount and the discharge amount of the mixed gas can be adjusted by the supply amount adjusting valve 8 or the discharge amount adjusting valve 9, respectively.

The reaction device 3 and the branching waveguide 2 are connected to each other via an applicator known per se.

In the present invention, the hydrogen oscillated from one microwave oscillator is supplied to the reaction chambers of the plasma generators of the same load so that the branched microwaves have the same intensity. The irradiation intensity of the mixed gas of the gas and the carbon source gas is usually 0.1 kw or more,
Preferably, they are used by branching so that each has a power of 0.2 kw or more. The irradiation intensity per plasma generator is
If it is less than 0.1 kW, the deposition rate of diamond may be slow, or diamond may not be deposited.

The hydrogen gas is used by being mixed with the carbon source gas, and forms atomic hydrogen and the like by irradiation with microwaves.

The atomic hydrogen has the action of removing the carbon of the graphite structure that is deposited at the same time as the deposition of diamond, and the action of maintaining the SP ³ structure of the carbon atoms in the deposited diamond crystal even at high temperatures.

Examples of the carbon source gas include methane, ethane,
Paraffinic hydrocarbons such as propane and butane; Olefinic hydrocarbons such as ethylene, propylene and butylene;
Acetylene hydrocarbons such as acetylene and allylene; Diolefin hydrocarbons such as butadier; Alicyclic hydrocarbons such as cyclopropane, cyclobutane, cyclopentane and cyclohexane; Aromatic hydrocarbons such as benzene, toluene, xylene and naphthalene; Examples thereof include ketones such as acetone, diethyl ketone and benzophenone; alcohols such as methanol and ethanol; amines such as trimethylamine and triethylamine; carbon dioxide gas and carbon monoxide.

These may be used alone or in combination of two or more.

Among these, preferred are paraffin hydrocarbons such as methane, ethane and propane, ketones such as acetone and benzophenone, and amines such as trimethylamine and triethylamine, and particularly preferred are methane, acetone, methanol and trimethylamine. .

The concentration of the carbon source gas in the hydrogen gas is usually 0.1 to 2
It is 0 mol%, preferably 0.2 to 10 mol%. This concentration
If it is less than 0.1 mol%, the deposition rate of diamond may be slow, or diamond may not be deposited. On the other hand, if it exceeds 20 mol%, non-diamond carbon such as graphite may be precipitated.

The reaction pressure in the method of the present invention, that is, the pressure in the reaction chamber is usually 0.001 to 1000 torr, preferably 1 to 800.
is torr. When the reaction pressure is lower than 0.001 torr, the deposition rate of diamond may be slow or the diamond may not be deposited.

The temperature of the substrate surface is usually 400 ° C to 1000 ° C, preferably 600 ° C to 950 ° C. If this temperature is lower than 400 ° C., the deposition rate of diamond may be slow, or diamond may not be deposited. On the other hand, when the temperature exceeds 1000 ° C., the deposited diamond is conversely scraped by etching, and the deposition rate of diamond may be slowed down.

In order to manufacture diamond with the synthesizer of the present invention, the following may be done.

The mixed gas of the hydrogen gas and the carbon source gas is
The gas is supplied into the reaction chamber 4 of the plasma generator 3 having the same load shown in FIG.

Then, the microwave oscillated from the microwave oscillator 1 is branched into the mixed gas supplied into the reaction chamber 4 by the branch waveguide 2 so that the branched microwaves have the same intensity, and the same. The mixed gas is activated by irradiating each plasma generator 3 of the load to form plasma.

The activated mixed gas reaches the surface of the substrate 7 and deposits diamond on the surface of the substrate.

 The used reaction gas is exhausted by the exhaust device 6.

When the method of the first invention is carried out by the synthesizing apparatus of the second invention, a plurality of diamond thin films can be obtained at the same time, and the obtained diamond thin films can be suitably used, for example, for coating a cutting tool (bite). You can

[Effects of the Invention] According to the present invention, (1) since a plurality of diamond thin films can be simultaneously manufactured, an industrially advantageous method for synthesizing diamond can be provided. (2) Further, this manufacturing method In this case, since it is only necessary to branch and use the microwave, it is possible to simplify the synthesizer. (3) Furthermore, in the synthesizer used for implementing this synthesizer method, a single microwave oscillator is used in plural. Since it is used in common by the plasma generator, it is possible to provide a diamond synthesizing method and a synthesizing apparatus having various effects such as excellent production efficiency.

EXAMPLES Next, examples of the present invention will be shown to explain the present invention in more detail.

(Example 1) Methane gas and hydrogen gas were introduced into a reaction tube using a silicon wafer as a substrate.

Then, set the output of the microwave oscillator to 2.4kw, and
The bidirectional branch waveguide is used to branch the output into two directions so that the microwaves have the same intensity in each of the bifurcated branches, and the two outputs are further output to two sets of second bidirectional branch waveguides. By bifurcating in two directions, each of the bifurcated microwaves is bifurcated into 4 outputs so that each microwave has the same intensity,
w Continuously supplied and discharged. At this time, the amount of methane gas was 0.5 sccm and the amount of hydrogen gas was 100 sccm.

By depositing for 4 hours in this state, a thin film having a thickness of 2 μm was simultaneously obtained on each of the four substrates.

When the obtained thin films were analyzed by Raman spectroscopy, it was confirmed that no impurities other than diamond were present in any of the thin films.

(Example 2) The same procedure as in Example 1 was performed except that the methane gas was changed to ascent in Example 1, to simultaneously obtain thin films having a thickness of 10 μm on each of the four substrates. When the obtained thin films were analyzed by Raman spectroscopy, it was confirmed that no impurities other than diamond were present in any of the thin films.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a conceptual diagram showing the configuration of a diamond synthesizing apparatus of the present invention, and FIG. 1 (b) is an explanatory view showing an example of a plasma generator constituting the apparatus. It is a figure. 1 ... Microwave oscillator, 2 ... Branch waveguide, 3 ... Plasma generator.

Claims (2)

[Claims] 1. A method for synthesizing diamond, wherein plasma obtained from a hydrogen gas and a carbonic acid source gas by microwave irradiation in a plasma generator is introduced into a substrate surface to deposit diamond on the substrate surface. ,
A microwave oscillated from one microwave oscillator is branched into a plurality of microwaves so that the branched microwaves have the same intensity, and the branched microwaves are guided to a plurality of same-load plasma generators. A method for synthesizing diamond, characterized in that 2. A microwave oscillator for oscillating a microwave, and a branching waveguide for branching the microwave oscillated from the microwave oscillator into a plurality of microwaves so that each of the branched microwaves has the same intensity. A diamond synthesizing apparatus comprising: a plurality of plasma generators of the same load, each of which is connected to the branch waveguide and has a substrate for depositing diamond.