JPS61247696A - Device for vapor phase synthesis of diamond - Google Patents

Abstract

PURPOSE:To easily and exactly perform temp. control of a substrate and to permit the use of a large substrate by providing an induction heating coil for heating the substrate in addition to a microwave irradiating device for generating plasma in gas. CONSTITUTION:A microwave irradiating device 11 is connected to an end of a microwave waveguide 1 and a reaction chamber 2 is attached to another end of the waveguide 1. 12 is a shield comprising quartz glass. The reaction chamber 2 is constituted of a nonmetallic material such as quartz and connected to an exhaust device 21 interposing an exhaust pipe 20 and a flow control valve 24. A gas feed pipe 3 is connected to another end of the reaction chamber 2. Another end of the gas feed pipe 3 is connected to a gas feeding source 31 interposing a flow control valve 35 interposing each flow control valve 32, 33, and 34 provided to each branch pipe. Further, a substrate for depositing diamond 4 is arranged to the inside of the reaction chamber 2 and an induction heating coil 7 arranged to heat the substrate 4 is provided to the external periphery of the reaction chamber 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a diamond vapor phase synthesis apparatus that can easily and accurately control the temperature of a substrate on which diamond is deposited.

(Prior Art) Plasma CVD equipment using microwaves is used for forming thin films of metal oxide semiconductors, ceramics, organic materials, and the like. Many of these devices are designed to minimize heating and thermal effects on the substrate and formed film. 2. Plasma CVD necking is also applied to the vapor phase synthesis of diamond, but in this case, the lifetime of the radical species involved in the reaction mechanism is short, so the substrate must not be placed in the plasma. In order to promote diamond crystal growth,
The substrate temperature must be kept at a high temperature of 800 to 1000 degrees Celsius.

As the above-mentioned diamond synthesis device, for example, JP-A-59
The one shown in Japanese Patent No. 3098 is known. This is a microphone that transmits microwaves [near the tip of a single-wave waveguide is placed through a non-metallic reaction tube, and a diamond deposition substrate is placed inside the reaction tube. The irradiation generates plasma in the gas inside the reaction tube and heats the substrate.

The following process elements are involved in depositing diamond onto a substrate using the above apparatus.

(A> Make vacuum inside the reaction tube.

(B) A CH4-H2 mixed gas containing approximately 1% CH4 is flowed at a rate of approximately 50 mρ/min such that the pressure inside the reaction tube is approximately 50 Torr.

(C) Plasma is generated around the substrate by generating standing microwave waves in the reaction tube.

(D) The substrate itself is also induction heated using microwaves.

(E) The above conditions are set so that the temperature of the substrate is 800 to 1000'C.

The temperature of the substrate depends on the output of the microwave, the type of substrate, the gas flow rate, the gas pressure, etc. However, these parameters define the formation conditions such as the diamond growth rate, so when adjusting only the microwave as in the above system, it is necessary to simultaneously satisfy the above-mentioned predetermined substrate temperature and formation conditions. is difficult.

In addition, in the above device, since the reaction tube passes through the waveguide, the diameter of the reaction tube is the width of the waveguide (2450 Ml-1
The diameter of the reaction tube must be smaller than that of the waveguide J: in order to prevent microwave leakage. there were. For this reason, it has not been possible to increase the size of the substrate on which diamond is deposited.

(Purpose of the Invention) This invention was made to solve such conventional problems, and in addition to microwaves that are irradiated to generate plasma in gas, induction heating is used to heat the substrate. This makes it possible to easily and accurately control temperature, and also to increase the size of the substrate.

(Structure of the Invention) The present invention includes a microwave waveguide through which microwaves are transmitted, a reaction chamber attached to the tip of the waveguide, a gas supply source connected to the reaction chamber, and an exhaust gas source connected to the reaction chamber. The apparatus includes an apparatus, a substrate for diamond deposition placed inside a reaction chamber, and an induction heating coil placed around the outer periphery of the reaction chamber so as to heat the substrate by induction.

(Example) In FIG. 1, a microwave irradiation device 11 is connected to one end of a microwave waveguide 1, and a reaction chamber 2 is connected to the other end of the waveguide 1. 12 is a shield made of quartz glass.This reaction chamber 2 is made of a non-metal such as quartz, and an exhaust pipe 20 is connected to this reaction chamber 2. An exhaust device 21 is connected via a flow control valve /I, and a gas supply pipe 3 is connected to the other end of the reaction chamber 2.The other end of this gas supply pipe 3 is connected to a flow control valve 35 and It is connected to the gas supply source 31 via respective flow rate regulating valves 32, 33, 34 installed in the branch pipes.

Further, a diamond deposition substrate 4 is arranged inside the reaction chamber 2, and this substrate 4 is arranged on a support stand 5, which is supported by a support rod 6, and this support rod 6 is It is connected to a lid 8 which is removably attached to the reaction chamber 2. Further, an induction heating coil 7 is disposed at the outer periphery of the reaction chamber so as to inductively heat the substrate 4 .

Note that a cooling water passage may be formed in the support rod 6 so that the temperature of the substrate 4 can be adjusted by passing cooling water therethrough.

FIG. 2 shows another embodiment of the present invention, in which a diverging portion 19 whose diameter gradually increases is formed at the tip of the waveguide 1, and a reaction chamber 2 is connected to the tip. Zunawachi,
It is configured to prevent the cross-sectional area from rapidly increasing when moving from the waveguide 1 to the reaction chamber 2, and to gradually increase the cross-sectional area due to the widening portion 19. The configuration of the bar is similar to that in FIG. 1 above.

FIG. 3 shows yet another embodiment of this invention.

A magnet coil 70 is arranged further outside the induction heating coil 7 on the outer periphery of the reaction chamber 2, so that a magnetic field can be generated within the reaction chamber 2. That is, by forming a magnetic field, electrons are accelerated in the magnetic field, and a high plasma density is achieved by 1q. Therefore, the strength of the magnetic field is J:
Set to For example, if the microwave is 2450 MHz, it may be set to 875 Gauss. The rest of the structure is the same as that shown in FIG. Note that the magnet coil 70 described above can also be employed in the apparatus shown in FIG.

In the above configuration, a predetermined amount of Cl-14, 1-12 and inert gas are discharged by the flow rate regulating valves 32, 33, 34, respectively, and a predetermined CH4l-12U mixture gas flows through the flow 9.
The above-mentioned C1 to +4-1-12 mixed gas is supplied to the reaction chamber 2 at a predetermined pressure by being sent out from the 1 regulating valve 35 and sucked from the exhaust device 21. CI-1
The ratio of 4 to 112 is set, for example, to about 1%, and the gas is set to flow at a flow rate of 50 mρ/min so that the inside of the reaction tube 2 becomes about 50 orr.

In addition, the following hydrocarbons may be used in place of CI-(4). Namely, paraffinic saturated chain hydrocarbons such as ethylene, propane, butane, olefins such as ethylene, propylene, butylene, etc. Systemic unsaturated chain hydrocarbons,
Acetylenic unsaturated chain hydrocarbons such as acetylene and arylene, diolefinic unsaturated hydrocarbons such as arene and butadoene, alicyclic hydrocarbons such as cyclopropane, cyclopenkune, and cyclohexane, cyclobutadiene, benzene,
Aromatic hydrocarbons such as 1-luene, xylene, naphthalene, and cyclooctatetraene can be used.

Microwaves are sent from the two-way microwave irradiation device 11 through the waveguide 1, and are irradiated into the reaction chamber 2 at the tip of the waveguide, so that the antinode of the standing wave, that is, the place where the electric field is strongest, is located at the substrate 5. Let it happen.

Plasma is generated in the CHs-1-12 mixed gas supplied to the substrate 4 by this microwave irradiation. Further, the dielectric heating coil 7 is energized to heat the substrate 4. Although the substrate 4 is also heated by microwave irradiation, the microwave irradiation output is set to the most favorable conditions for depositing diamond on the substrate 4.
It is set according to the gas flow rate, type of substrate, etc. Therefore, the heating temperature of the substrate is compensated for by induction heating by energizing the coil 7, and the substrate 4 is heated to 800 to 1
Adjust to 000°C. Normally, a current with a frequency of about 100 Kl-1z may be passed through the coil 7.

As mentioned above, the most favorable conditions for diamond precipitation are set using microwaves, and the temperature control for the substrate is performed using a separate coil, so the overall conditions can be set accurately. And it can be done easily.

Example-1 The above figure 2! A reactor was used to supply CH4 gas, which was obtained by diluting H2 gas to 20% with 50 CCSH2 gas per minute, into the reaction chamber 2 at a flow rate of 5 cc per minute. The inside of reaction chamber 2 was adjusted to 50 Torr. Next, waveguide 1
Microwaves with a frequency of 2450 MH2 and an output of 1 KW were introduced through the tube to generate plasma. At the same time, while monitoring the temperature of the silicon wafer substrate 4 with an appropriate temperature measuring device, a high frequency wave with a frequency of 100KH2 is guided to the induction heating coil 7, and the output is adjusted to bring the temperature of the substrate 4 to 95.
It was kept at 0°C. When diamond was deposited on the substrate 4 in this manner for 3 hours, the formation of diamond particles with a diameter of about 1 μm was observed.

Example-2 Using the apparatus shown in Fig. 3 above, 1-12 gas was diluted to 20% with 1-42 gas at 50 CC per minute as a reaction gas.
H4 gas was supplied into the reaction chamber 2 at a flow rate of 5 cc/min.

The inside of reaction chamber 2 was adjusted to 50 Torr, and the temperature was 87 Torr.
The coil 70 was energized so that a magnetic field of 5 Gauss was generated. Next, microwaves with a frequency of 2450 MHz and an output of IKW were introduced through the waveguide 1 to avoid generating plasma. While monitoring the temperature of the silicon wafer board 4 using an appropriate temperature measuring device, the same wave number of 100 Kl- was measured.
The high frequency of I7 was guided to the induction heating coil 7, and the output was adjusted to maintain the temperature of the substrate 4 at 950°C. When diamond was deposited on the substrate 4 for 3 hours in this way,
The formation of diamond particles with a diameter of about 1 μm was observed.

(Effects of the Invention) As explained above, the present invention provides a non-metallic reaction chamber at the tip of a microwave waveguide and a non-metallic reaction chamber disposed inside the microwave waveguide.
The substrate for diamond deposition is heated by an induction heating coil placed around the outer periphery of the reaction chamber, and a heating means is provided separately from the microwave irradiated to generate plasma in the reaction gas. The temperature of the substrate can be controlled easily and accurately because the substrate is placed in a reaction chamber separate from the waveguide. It is possible to use a large board without receiving any damage. Furthermore, the above-mentioned neck strap has various features as described below.

(A) Vacuum the reaction chamber (e.g. 10' Tor
Gases such as N2.02 and N20 adsorbed on the surface of the substrate can be removed by keeping the temperature at 100 Ω and operating the induction heating coil.

(B) Induction heating coil and microphone () The induction heating coil is used to operate the Hatera irradiation head, introduce gas such as argon at low pressure, and generate argon plasma in the reaction chamber. It is possible to clean the surface of the substrate more efficiently than in the case where there is no such thing.

(C) By changing the frequency of the high frequency input to the a conductive heating coil, only the substrate can be selectively heated.

(D) After depositing diamond on the W plate, the induction heating coil can be operated to heat-treat the substrate.

[Brief explanation of drawings]

FIG. 1 is an overall explanatory diagram showing an embodiment of this invention, = 12
- Figure 2 is a partial explanatory diagram showing another embodiment of the invention;
The figure is a partially explanatory view showing still another embodiment. DESCRIPTION OF SYMBOLS 1... Waveguide, 2... Reaction chamber, 3... Gas supply pipe, 4... Substrate, 7... Induction heating coil, 11...
・Microwave irradiation device, 20...υ1 trachea, 21...
・1 air device, 31... gas supply source, 70... magnet coil. Patent Applicant Kobe Steel Co., Ltd. Agent Patent Attorney Etsushi Kotani Patent Attorney Chief 1) Masayuki Patent Attorney Yasuo Itaya Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] 1. A microwave waveguide through which microwaves are transmitted, a reaction chamber attached to the tip of this waveguide, a gas supply source and exhaust device connected to this reaction chamber, and a gas supply source and exhaust device arranged inside the reaction chamber. 1. A diamond vapor phase synthesis apparatus comprising: a diamond deposition substrate; and an induction heating coil disposed around the outer periphery of a reaction chamber so as to inductively heat the substrate. 2. A microwave waveguide through which microwaves are transmitted, a reaction chamber attached to the tip of this waveguide, a gas supply source and exhaust device connected to this reaction chamber, and a gas supply source and exhaust device arranged inside the reaction chamber. It has a substrate for diamond precipitation, an induction heating coil arranged around the outer periphery of a reaction chamber to inductively heat the substrate, and a magnet coil arranged around the outer periphery of the reaction chamber so as to form a magnetic field inside the reaction chamber. A diamond vapor phase synthesis device featuring: