JPH11228290A - Diamond growing apparatus utilizing microwave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diamond growing apparatus capable of increasing a growth rate of a diamond as quick as possible and unifying the crystal of the diamond. SOLUTION: This diamond growing apparatus utilizing a microwave plasma generation device having a coaxial line 21 for transmitting a microwave has a gas supplying tube 51 for supplying a component gas for the diamond, installed in an inner conductor 21b of the coaxial line 21 so that the component gas may be directly supplied to a microwave plasma 25 generated at the tip part of the coaxial line 21, and the whole supplied component gas may be chemically reacted to grow the diamond on the upper face of a material 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for heating a specific gas such as hydrogen gas or methane gas by microwave plasma and chemically growing diamond on an object by a chemical reaction. The present invention relates to a diamond growth apparatus capable of increasing the growth rate of diamond and making the diamond crystal uniform by directly supplying the diamond into plasma.

[0002]

2. Description of the Related Art FIG. 5 is a schematic diagram showing a first conventional example in which diamond is grown using a cavity resonator type plasma generating apparatus. The plasma generator is a rectangular waveguide 1
1 transmits a microwave MW to generate a plasma 13 in the resonance chamber 12.

The waveguide 11 has one end connected to the resonance chamber 12 and the other end connected to a microwave oscillator via an impedance matching device. A partition 14 made of a dielectric material such as quartz glass is provided between the waveguide 11 and the resonance chamber 12 so that the resonance chamber 12 has an airtight structure.

Further, the resonance chamber 12 has a vacuum pump 15
The air is exhausted to form a vacuum chamber, and the resonance chamber 12 contains hydrogen (H ₂ ) gas and methane (CH ₄ ).
Gas supply pipe 1
Supplied from 6. The object 17 (for example, a silicon wafer or the like) on which diamond is to be grown is placed in the resonance chamber 1.
2 is held in a light emitting portion of the microwave plasma 13 generated in the inside.

[0005] In such a diamond growth apparatus, when microwave MW is transmitted from the waveguide 11, the plasma 1 is placed in a part of the resonance chamber 12 where the electric field strength of the microwave becomes strong.
3 occurs. The generation of the plasma 13 heats element gases such as hydrogen gas and methane gas, and causes diamond to grow on the surface of the object 17 by a chemical reaction.

FIG. 6 is a schematic configuration diagram showing a second conventional example for growing diamond using a coaxial line type plasma generator, and FIG. 7 is a sectional view taken along line AA in FIG. The plasma generator is configured to transmit the microwave MW through the coaxial line 21 including the outer conductor 21a and a rod-shaped inner conductor 21b passing through the center of the outer conductor 21a. That is, the coaxial line 21 is connected to the microwave oscillator via the impedance matching unit 22.

[0007] One end of the coaxial line 21 is connected to a vacuum chamber 23. The vacuum chamber 23 is separated from the coaxial line 21 by a partition member 24 in order to make the vacuum chamber 23 airtight. The partition member 24 is formed of a dielectric material such as quartz glass that transmits microwaves and does not absorb microwave power.

The above-mentioned inner conductor 21b of the coaxial line 21
The tip 21c of the vacuum chamber 2 passes through the partition member 24.
3 has entered. The distal end portion 21c protruding into the vacuum chamber 23 has a wavelength (λ /
4) The length is determined to be + n · (λ / 2). (N =
0, 1, 2, 3,...) The tip of the tip 21c has a sharp shape to concentrate the microwave electric field and to easily generate the plasma 25.

The above-mentioned vacuum chamber 23 is provided with a vacuum pump 2 for adjusting the degree of vacuum to about 1 Torr to several hundred Torr.
6 and a gas supply pipe 27 for supplying a diamond element gas such as hydrogen (H ₂ ) gas or methane (CH ₄ ) gas to the vacuum chamber 23.

On the other hand, an object (for example, a silicon wafer) 28 on which diamond is to be grown
A heater 29 for heating the object 28 so as to mount the object 28 is provided. The object 28 is arranged outside the light emitting portion of the plasma 25, that is, outside the light emitting portion of the plasma 25 where diamond can be grown. 30 is heater 2
9 feed lines.

In the conventional diamond growing apparatus, when the microwave MW is transmitted by the coaxial line 21, the microwave electric field becomes strong at the tip of the tip 21c of the internal conductor 21b, and the plasma 25 is generated. As a result, the diamond element gas is heated by the plasma 25, the excited gas falls onto the object 28, and diamond is grown by chemical vapor deposition. The objects 17 and 28 for growing diamond are placed in a container of an alcohol solution mixed with diamond powder, and a pre-process is performed by applying ultrasonic waves to the container.

[0012]

In the diamond growth apparatus shown as the first conventional example, element gases such as hydrogen gas and methane gas are supplied to the resonance chamber 12, and only the element gases heated by the plasma 13 and chemically reacted are supplied. It grows on the surface of the object 17 as diamond.

For this reason, diamond is generated only by the element gas which naturally enters the plasma 13 and the plasma 13
The other element gases which do not enter the vacuum pump are sucked out by the vacuum pump 15, and there is a problem that the diamond growth rate is reduced.

The diamond growth apparatus shown as the second conventional example supplies element gases such as hydrogen gas and methane gas to the vacuum chamber 23, so that the diamond growth rate is slow as in the first conventional example. In addition, there is a problem that it is difficult to form diamond having a uniform crystal.

That is, in the case of this diamond growth apparatus, the element gas heated by the plasma 25 is the object 28
Grows on the surface of the diamond to grow diamond. In addition to the gas that falls into the object 28 after entering the plasma 25, there is a component gas that falls onto the object 28 without touching the plasma 25 at all. As a result, the crystal of the diamond is affected by this, and becomes a crystal of various shapes, and the diamond grows.

In view of the above circumstances, an object of the present invention is to provide a diamond growth apparatus of this kind which can increase the diamond growth rate as much as possible and make the diamond crystals uniform.

[0017]

According to the present invention, there is provided a diamond growth apparatus for heating a gas supplied into a vacuum chamber by microwave plasma and growing diamond on an object by a chemical reaction. A diamond growth apparatus characterized by comprising a gas supply means for guiding the gas into the microwave plasma is proposed.

[0018]

In the above-described diamond growth apparatus, all gases supplied into the vacuum chamber are guided into the microwave plasma. As a result, there is no gas discharged without touching the plasma, and all the gas is heated by the plasma and contributes to the growth of diamond, so that the growth rate of diamond is high.

Further, since a gas which does not come into contact with the plasma other than the gas heated by the plasma does not fall on the object, diamond having a uniform crystal can be produced.

[0020]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention using a cavity resonator type plasma generator.

The diamond growth apparatus according to the first embodiment has a gas supply pipe 41 in which a gas supply port 41a is disposed at the center of the microwave plasma 13. The rest of the configuration is the same as that of the first conventional example shown in FIG.

In the diamond growth apparatus configured as described above, the element gases such as hydrogen gas and methane gas supplied to the resonance chamber 12 are all supplied to the plasma 13 by the gas supply pipe 41.
Sent to the center of As a result, all the supplied element gases enter the plasma 13 and are heated by the plasma 13, whereby diamond is deposited on the surface of the object (eg, silicon wafer, diamond substrate, etc.) 17 by chemical vapor deposition. I do.

Accordingly, a diamond growth apparatus having a high diamond growth rate and high diamond generation efficiency can be obtained. The gas supply pipe 41 is made of a material such as quartz glass, carbon, and a high melting point metal.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the present invention using a coaxial line type plasma generator, and FIG. 3 is a sectional view taken along line BB in FIG. The diamond growth apparatus according to the second embodiment includes an inner conductor 21b of the coaxial line 21.
The gas supply pipe 51 is provided in the inside. In addition,
The rest of the configuration is the same as that of the second conventional example shown in FIGS. 6 and 7, and therefore the same members and portions are denoted by the same reference characters and description thereof will be omitted.

The gas supply pipe 51 is made of quartz glass,
It is made of a material such as carbon or a high melting point metal, and the tip supply port at the tip is located at the tip of the tip 21c of the internal conductor 21b. In the diamond growth apparatus configured as described above, all element gases such as hydrogen gas and methane gas supplied to the vacuum chamber 23 are sent into the plasma 25 by the gas supply pipe 51.

As a result, all the supplied element gases enter the plasma 25 and are heated by the plasma 25,
The element gas falls onto the object 28, and diamond is grown on the surface of the object (silicon wafer, diamond substrate, etc.) 28 by chemical vapor deposition. From this, the diamond growth rate is high, and the diamond is plasma 25
Is grown only by the element gas heated by the heat treatment, thereby producing a uniform crystal diamond.

FIG. 4 shows that the gas supply port 61a is connected to the plasma 25.
FIG. 10 is a schematic configuration diagram showing a third embodiment provided with a gas supply pipe 61 disposed near the outer periphery of the light emitting portion, and the other configuration is the same as that of the second conventional example. Even with this configuration, almost all of the supplied element gas enters the plasma 25, so that substantially the same effects as those of the diamond growth apparatus of the second embodiment can be obtained.

The gas supply pipe 41 provided in the first embodiment shown in FIG. 1 can obtain substantially the same effect by disposing the gas supply port 41a near the outer periphery of the light emitting portion of the plasma 13. it can. Also, in the first embodiment using the cavity resonator type plasma generator, if the object 17 is mounted on a heater and heated, as in the second embodiment, the light emitting portion of the plasma 13 is used. An object 17 can be placed outside to grow the diamond.

Although the embodiment of the present invention has been described above, the diamond produced by the present invention has a hardness,
It has excellent insulation properties, is suitable for semiconductor heating and circuit board materials, and can be used as an optical material because of its light-transmitting properties over a wide wavelength range.

The diamond thus produced is a semiconductor having a wide hand gap of 5.45 (eV) and a high carrier mobility, and thus is suitable as a high-performance device such as a high-temperature transistor.

Energy of particles in microwave plasma
According to the present invention, the surface of a substrate or the like to be subjected to CVD (chemical vapor deposition) is hardly damaged, and various kinds of materials are used. CVD processing becomes possible.

When the present invention is implemented as in the second and third embodiments, the tip portion 21c of the internal conductor 21b is made of carbon, tungsten, molybdenum, or the like.
It is desirable to be made of a conductive material made of a high melting point metal material such as tantalum.

[0033]

As described above, in the diamond growth apparatus according to the present invention, since all of the supplied element gases are guided into the microwave plasma, the growth rate of diamond can be increased and the crystal can be made uniform. Can be produced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention using a cavity resonator type plasma generator.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the present invention using a coaxial line type plasma generator.

FIG. 3 is a sectional view taken along line BB in FIG. 2;

FIG. 4 is a schematic configuration diagram showing a third embodiment of the present invention using a coaxial line type plasma generator.

FIG. 5 shows a first example using a cavity resonator type plasma generator.
FIG. 2 is a schematic configuration diagram showing a conventional example of FIG.

FIG. 6 is a schematic configuration diagram showing a second conventional example using a coaxial line type plasma generator.

FIG. 7 is a sectional view taken along line AA in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Waveguide 12 Resonant chamber 13 Plasma 14 Partition wall 15 Vacuum pump 17 Object 21 Coaxial line 21a External conductor 21b Internal conductor 23 Vacuum chamber 24 Partition member 25 Plasma 28 Object 29 Heater 41, 51, 61 Gas supply pipe

Claims (1)

[Claims] 1. A diamond growth apparatus for heating a gas supplied into a vacuum chamber by microwave plasma to grow diamond on an object by a chemical reaction, comprising a gas supply means for introducing the gas into the microwave plasma. A diamond growth apparatus characterized in that: