JPH0627343B2 - Forced convection type plasma reactor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a forced convection type plasma reactor used in a synthesis method utilizing plasma.

2. Description of the Related Art As a conventional plasma reactor, a reaction chamber 2 as shown in FIG. 2 is made horizontal, and a substrate 8 is vertically provided in the reaction chamber 2.
A plasma is generated by induction heating 6 in the reaction chamber, and the reaction gas is introduced from the introduction pipe 11 toward the substrate. In addition, the reaction chamber 2 as shown in FIG. 3 is made vertical, and the substrate (or powder collector) 8 is provided horizontally in the reaction chamber 2.
A reactor in which plasma is generated by induction heating 6 in the reaction chamber 2 and a reaction gas is introduced through an upper introduction pipe 11 is used.

However, in these reactors, since the direction of the convection generated by heating the plasma and the direction of the flow of the introduced gas do not match, the flow of the gas is disturbed, which hinders the efficient use of the raw material reaction gas, It also causes a decrease in reproducibility in experiments.

OBJECT OF THE INVENTION The present invention has been made to solve the drawbacks of the conventional plasma reactor, and its purpose is to make the plasma flow direction and the reaction gas flow direction coincide with each other and not be affected by plasma convection. In this way, it is possible to reduce the disturbance of the gas flow, improve the reproducibility in experiments, and improve the utilization efficiency of the raw material gas, and control the gas flow velocity by changing the input to the plasma. To provide a furnace.

Structure of the Invention In the forced convection type plasma reactor of the present invention, as shown in FIG. 1, a reaction chamber 2 is provided above a plasma generator 3 having a plasma jet port 4 for jetting plasma upward. A cooler 1 is provided on the top of the chamber, a substrate or a powder collector 8 is installed in the reaction chamber 2 so as to face the plasma jet port 4, and a space is provided between the plasma jet port 4 and the substrate or the powder collector 8. The above object was achieved by providing the reaction gas introduction pipe 11 for introducing the reaction gas in the same direction as the plasma jet direction.

The plasma generator 3 is surrounded by a cooling (for example, water cooling) jacket 5, and a plasma is generated by inputting a high frequency wave 6 from the outer periphery thereof. Gas for plasma (eg He +
H ₂ ) is introduced into the plasma generation part through the introduction pipe 7, and the generated plasma is ejected from the plasma ejection port 4 toward the information. A substrate 8 is held in the reaction chamber 2 by a substrate support 9, and the substrate 8 is heated by a heater 10 to an appropriate temperature.
In 11, a reaction gas is introduced through a reaction gas introduction pipe in the same direction as the plasma flow. 12 is an outlet. Although the drawing shows the case where the substrate is installed, when collecting the reaction product as a powder, a powder collector is used instead.

In the operation of this plasma reactor, a plasma gas and a reaction gas are usually steadily flowed, and at the same time, exhaust gas is used from an exhaust port to be used as an open system. At that time, a desired gas pressure is obtained by controlling the exhaust rate and the reaction gas flow rate. Introduce a gas for plasma into the plasma generation part to turn it into plasma,
Plasma is ejected from the plasma ejection port. On the other hand, the reaction gas undergoes a decomposition reaction due to plasma and is deposited on the substrate. The residual gas is cooled by a cooler provided in the upper part of the reaction chamber, descends to the lower part of the reaction chamber, enters the plasma generation part, and is repeatedly turned into plasma, while part of them is exhausted.

Effects of the Invention According to the plasma reactor of the present invention, in the reaction chamber,
Since the plasma flow direction and the reaction gas flow direction are the same and are not affected by convection due to plasma heating, there is little disturbance by the gas flow in the reaction chamber, improving the reproducibility in experiments and utilizing the reaction gas. You can increase efficiency.

Further, the flow rate of the reaction gas in the reaction chamber is controlled only by the introduction pressure of the reaction gas in the conventional plasma reactor, but in the plasma reactor of the present invention, the flow rate of the reaction gas is also controlled by the plasma injection force. Since it can be obtained, it can be controlled by changing the input of plasma, and the flow rate of the reaction gas can be easily adjusted.

Example 1. Using the reaction furnace shown in FIG. 1, diborane as a source gas,
Using hydrogen and helium mixed gas as plasma gas, total pressure 2 Torr, substrate temperature 870 ℃, plasma input 800 W
, Silicon substrate, Helium diluted 5% dibon flow rate 30SCC
Hard boron thin films were prepared under the condition of M. The growth rate of the film reached 15 μm / h. The film was metallic and homogeneous, the adhesion to the substrate was good, and the deposition efficiency of the reaction gas was 60% or more.

On the other hand, the vapor deposition efficiency of the reaction gas when using the plasma reactor shown in FIG. 2 under the same conditions as described above was 1/10 or less.

Example 2. Using the reaction furnace shown in FIG. 1, diborane as a source gas,
Using hydrogen and helium as plasma gas, total pressure 2
Boron needle-like crystals were obtained at a total flow rate of 100 SCCM, a substrate temperature of 880 ° C., a plasma input of 2 kW, a silicon wafer as a substrate, and a helium-diluted 5% dibon flow rate of 20 SCC.

[Brief description of drawings]

FIG. 1 is an embodiment diagram of a forced convection plasma reactor of the present invention, and FIGS. 2 and 3 are conventional plasma reactors. 1: Cooler, 2: Reaction chamber, 3: Plasma generator, 4: Plasma ejection port, 5: Cooling jacket, 6: High frequency input, 7: Plasma gas introduction pipe, 8: Substrate, 9: Substrate support, 10: heater, 11: reaction gas introduction pipe, 12: exhaust port.

Claims (1)

[Claims] 1. A reaction chamber is provided above a plasma generator having a plasma ejection port for ejecting plasma upward, and a cooler is provided at the top of the reaction chamber, and a substrate or powder is provided in the reaction chamber so as to face the plasma ejection port. Forced convection characterized in that a body collector is installed and a reaction gas introduction pipe for introducing the reaction gas in the same direction as the plasma ejection direction is provided between the plasma ejection port and the substrate or powder collector. Type plasma reactor.