JP2969439B2 - Diamond growth equipment using microwave plasma - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for growing diamond on an object by chemically reacting a specific gas with microwave plasma, and more particularly, to arranging an object outside a light emitting portion of the plasma, and applying the object to a plasma. The present invention relates to a diamond growing apparatus capable of obtaining a uniform diamond distribution and various crystal conditions of diamond by heating.

[0002]

2. Description of the Related Art In a conventional diamond growth apparatus utilizing microwave plasma, a hydrogen (H ₂ ) gas, a helium (He) gas, and an argon (A) gas, which are diamond component gases, are placed in a vacuum chamber for generating microwave plasma.
r) An inert gas such as a gas, a hydrocarbon gas such as a methane (CH ₄ ) gas, an alcohol gas, or the like is supplied, and the element gas chemically reacted by the microwave plasma is supplied into the light emitting portion of the microwave plasma. It is configured to grow on the disposed surface body (object). When the temperature of the surface body is heated to about 900 ° C. by the microwave plasma, the gas excited by the plasma flows over the surface body heated to about 900 ° C., and diamond grows on the surface body.

[0003]

In the above-described diamond growth apparatus, the elemental gas is chemically reacted by the energy of the microwave plasma, and the surface is heated by this energy. And the temperature distribution is not uniform.

That is, even if the surface body is smaller than the microwave plasma sphere (light emitting portion), a temperature distribution due to the microwave plasma can be formed on the surface body. From this,
Depending on the location on the surface body, the growth rate of the diamond is high or low, and the distribution of the crystal state is slightly different.

[0005] On the other hand, the size of microwave plasma depends on the degree of vacuum, but the diameter is limited to 50 mm in the vicinity of 1 Torr to 50 Torr. The plasma is generated so as to be continuously arranged, but the uniformity of the plasma tends to be disturbed at the overlapping portion of each microwave plasma sphere and the diamond that grows on the surface body corresponding to this portion It is difficult to make the crystal and growth rate the same as in other parts.

As a result, it becomes difficult to grow a uniform crystal diamond at the same growth rate over the entire surface of a large surface.

Another problem of the above-described diamond growth apparatus is that the microwave plasma and the heater
It is difficult to use together.

As a condition for stably generating microwave plasma, there is known a generation method according to the theory of cavity resonance. However, since this generation method uses a resonance chamber for generating microwave plasma, this resonance method is used. If the structure of the chamber is any inconvenience to the generation of microwave plasma, or if there is something in the resonance chamber that interferes with the microwave, the microwave plasma will not be generated at the intended position .

For this reason, if a heater for heating the surface body is installed in the microwave plasma chamber, the conditions for generating the microwave plasma are changed, and it is extremely difficult to control the position of the microwave plasma. The plasma disappears or plasma is generated at the edge of the heater structure.

As a result, there is a problem in installing a heater together with a surface member in the light emitting portion of the microwave plasma or in bringing the light emitting portion of the microwave plasma into contact with the heater.

According to the present invention, in view of the above situation, diamond can be grown into an object of an arbitrary size.
It is another object of the present invention to provide a diamond growth apparatus using microwave plasma that can obtain diamond with uniform distribution and crystal growth and can obtain diamond with various crystals by arbitrarily changing the growth temperature. And

[0012]

Since the present invention SUMMARY OF] is to achieve the above object, the diamond growth apparatus for growing a diamond specific gas supplied to the vacuum chamber by a chemical reaction by microwave plasma onto an object, an external
A coaxial line consisting of a conductor and an inner conductor, and
Therefore, a vacuum chamber for supplying microwave energy is included.
Concentrate the microwave electric field at the tip of the inner conductor of the coaxial line
To generate microwave plasma in the vacuum chamber.
The plasma generating means is provided, Rutotomoni provided those bodies Ru grown diamond <br/> Mond and disposed in the vacuum chamber to the light emitting portion outside of the microwave plasma, the object to be - data - heated by structure We propose a diamond growth apparatus characterized by the following.

In the diamond growing apparatus constructed as described above, the object on which diamond is grown is heated by a heater, and the element gas is chemically reacted by microwave plasma. From this, the temperature distribution of the whole object becomes uniform, and the crystal of the growing diamond is made uniform.

Further, since an object on which diamond is to be grown is disposed outside the light emitting portion of the microwave plasma and the entire object is uniformly heated by a heater, the gas excited by the plasma is deposited on the object. And pour it. As a result, even if a plurality of microwave plasmas are continuously arranged and generated, the influence of the non-uniformity of the plasma distribution on the object is small. It is possible to grow a diamond of a suitable crystal.

Further, by changing the object temperature by adjusting the heater heating, diamonds in various crystalline states can be grown.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a simplified side view of a diamond growth apparatus shown as an embodiment, and FIG.
FIG. 3 is a sectional view taken along line A.

In these drawings, reference numeral 11 denotes a coaxial line, which comprises a cylindrical outer conductor 11a and an outer conductor 1a.
1a and a rod-shaped inner conductor 11b passing through the center of the inner portion. A coupler 12 is connected to one end of the coaxial line 11, and a vacuum chamber 13 whose diameter is larger than that of the external conductor 11a is connected to the other end. The coupler 12 is connected to a microwave oscillator by a coaxial line 14.

In order to keep the vacuum chamber 13 airtight, the inside of the vacuum chamber 13 and the inside of the coaxial line 11 are partitioned by a circular partition member 15. This partition member 15 is provided at the lower end of the outer conductor 11a.
It is provided in the outer conductor 11a at a slightly higher position , and is formed of a dielectric material such as quartz glass or ceramic that transmits microwaves and does not absorb microwave power .

The inner conductor 11b of the coaxial line 11, specification of the tip portion 11c through the center portion of the partition member 15 described above
The cutting member 15 protrudes toward the vacuum chamber 13.
The length of the internal conductor 11b is n · (λ / 2).
(N = 0,1,2,3 ·····) suited to vacuum chamber 13
The length of the tip 11c protruded from the tip 11c is (λ / 4) + n · (λ / 2) with respect to the wavelength λ of the microwave so that the microwave electric field is concentrated at the tip of the tip 11c. Has become. (N = 0, 1, 2, 3, ...)

Λ is a microwave frequency of 2450 M
It becomes 122.4 mm at Hz. The tip of the tip 11c of the internal conductor 11b is preferably formed to be sharp so that plasma is easily generated.

On the other hand, the above-mentioned vacuum chamber 13 has a pressure of 1 Torr.
A vacuum pump 16 for adjusting the degree of vacuum to about 50 Torr is provided, and a hydrogen (H ₂ ) gas and methane (CH ₄ ) for growing diamond are provided in the vacuum chamber 13.
It is designed to supply gas.

Further, inside the vacuum chamber 13, a surface body (object) 17 for growing diamond and a surface body 1
Heater for heating the surface body 17 by assembling 7
18 are provided. In particular, the surface body 17 is located outside the light emitting portion 19 where the plasma is generated, that is,
The structure is arranged near the light emitting portion 19 where diamond can be grown, and the gas excited on the surface member 17 allows the diamond to grow. In addition, 2
Numeral 0 denotes a conductive line for supplying electric power to the heater 18.

In the above-described diamond growth apparatus, the microwave power is output from the microwave oscillator, whereby the microwave is matched by the coupler 12 and transmitted to the coaxial line 11.

At this time, since the phase of the voltage is rotated by λ / 4 at the position of the partition member 15, the strength of the voltage is low in a situation where a standing wave is standing. While the generation of plasma is suppressed, the inner conductor 1
The microwave voltage becomes maximum at the tip of the tip portion 11c of 1b, and plasma (light emitting portion 19) is generated.

Therefore, the hydrogen gas and the methane gas undergo a chemical reaction by this plasma to grow diamond on the upper surface of the surface member 17. In this case, since the surface body 17 is disposed near the plasma light emitting unit 19, the surface body 1
7 is substantially uniform, and the entire surface body 17 is heated by the heater 18, so that the diamond growth rate and the crystal of the entire surface body are uniform. Becomes

If the surface member 17 is within the range in which diamond can be grown, the further away from the plasma light emitting portion 19, the more uniform the growth rate and the crystal.

Further, in the diamond growth apparatus configured as described above, even if the heater 18 is disposed in the vacuum chamber 13, the plasma generation conditions are not affected and the plasma is kept stable. , The surface body 17 by the heater 18
By adjusting the heating temperature, diamond in various crystalline states can be grown.

The structure for forming the heater 18 does not need to be designed with many restrictions in consideration of microwaves, and various equipments for generating diamond are installed near the plasma light emitting portion 19. For this reason, know-how in the design of an ordinary vacuum apparatus that does not use microwaves can be adopted.

As an example, an experimental example in which diamond is grown on a silicon wafer substrate will be described. In this case, a silicon wafer-substrate was set as the surface member 17, and the tip 11c of the internal conductor 11b was formed of a carbon material made of carbon (C). And the degree of vacuum 50To
rr, hydrogen gas 98%, methane gas 2%, input microwave output 200W, silicon wafer-substrate temperature 900 ° C,
It was confirmed that a single crystal diamond having a size of about 2 μm was grown by setting the deposition time to 1 hour.

It has been found that the diamond thus grown has a high purity and a very good crystalline state. When the tip 11c of the inner conductor 11b is formed of a conductive material other than the carbon material, the purity of the diamond is slightly lowered, but it has been found that the crystal state is also good in this case. The tip 1 of the inner conductor 11b
It is preferable that 1c be detachable so that it can be replaced with another material.

On the other hand, in the above-described diamond growth apparatus, the cross-sectional area (cross-section in FIG. 1) of the plasma light emitting portion 19 and the cross-sectional area (cross-section in FIG. 1) of the coaxial line 11 may be formed to have the same size. Since it is possible, by arranging a large number of coaxial lines 11 without gaps as shown in FIG. 3, the plasma light emitting section 19 becomes planar as shown in FIG.

3 and 4, reference numeral 21 denotes a group of coaxial lines, 21b denotes a tip of each internal conductor of the group of coaxial lines 21, 22 denotes a plasma light emitting unit, 23 denotes a wide-area surface member on which diamond is grown, Reference numeral 24 denotes a heater for heating the surface member 23. The plasma light emitting section 22 is generated in a vacuum chamber as in FIG.
Reference numeral 4 is disposed in the vacuum chamber.

With this configuration, even if the surface member 23 is not separated from the plasma light emitting portion 22, the distribution of the action of the plasma on the entire surface member becomes uniform, and the surface member 23 has a uniform surface over a wide area. It is possible to grow a diamond of a suitable crystal.

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 heat sink and circuit board materials of semiconductors, and can be used as an optical material because it has a wide wavelength range of light transmission. The diamond thus produced has a band gap of 5.4.
Since the semiconductor has a carrier mobility as high as 5 (eV), it 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 subjected to CVD (Chemical Vapor Deposition) is less likely to be damaged, and is suitable for a wide variety of materials. Is possible.
Products having such a complicated surface structure, regardless of size, can be sufficiently subjected to the CVD process.

Also, in the diamond growth apparatus shown in FIGS. 1 and 3, even if the surface body and the heater are installed in the plasma light emitting portion, the surface body is hardly affected by the generation of plasma. It is possible to adopt a configuration in which it is brought into contact with the plasma light emitting unit or provided in the plasma light emitting unit.

[Brief description of the drawings]

FIG. 1 is a side view of a diamond growth apparatus shown as an embodiment.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a schematic diagram of a diamond growth apparatus in which a large number of coaxial lines for generating microwave plasma are integrated, and plasma is generated by a group of coaxial lines.

FIG. 4 is a schematic diagram showing a state viewed from below a plasma light emitting unit where the above-described coaxial line group is generated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Coaxial line 11a Outer conductor 11b Inner conductor 11c Tip part 12 Coupler 13 Vacuum chamber 17 Surface body 18 Heater 19 Plasma light emitting part 21 Coaxial line group 22 Plasma light emitting part 23 Surface body 24 Heater

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-85092 (JP, A) JP-A-3-16998 (JP, A) JP-A-4-48928 (JP, A) JP-A-4- 214904 (JP, A) JP-A-5-239655 (JP, A) JP-A-6-316491 (JP, A) JP-A-7-106266 (JP, A) Table 7-506799 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C30B 29/04

Claims (1)

(57) [Claims] 1. A specific gas supplied to the vacuum chamber by a chemical reaction by microwave plasma in the diamond growth apparatus for growing diamond on the object, an external
A coaxial line consisting of a conductor and an inner conductor, and
Therefore, a vacuum chamber for supplying microwave energy is included.
Concentrate the microwave electric field at the tip of the inner conductor of the coaxial line
To generate microwave plasma in the vacuum chamber.
The plasma generating means is provided, Rutotomoni provided those bodies Ru grown diamond <br/> Mond and disposed in the vacuum chamber to the light emitting portion outside of the microwave plasma, the object to be - data - heated by structure A diamond growth apparatus characterized in that: