JPS60229333A - Vapor growth device - Google Patents

Abstract

PURPOSE:To remove unreactive raw material gas at a vapor growth device by a method wherein a supplementary heating parts is provided to the downstream part of a crystal substrate, and a heating means is provided to the outside of a reaction tube provided with the parts thereof. CONSTITUTION:A supplementary heating parts 5 is provided as to enlarge the contact area with raw material gas to the downstream part of a crystal substrate 2 put in a vapor growth reaction tube 1. A heating means, namely a high- frequency coil 6 is provided to the outside of the reaction tube 1 provided with the parts 2. Accordingly, unreactive gas can be thermally decomposed, and possibility to cause a danger to the human body of an operator is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a vapor phase growth apparatus, and in particular to a vapor phase growth apparatus used in the manufacturing process of semiconductor elements, etc., which uses harmful gases such as alcin-fusun lines. be.

(Prior art and its problems) Thin film growth is one of the extremely important steps in the production of devices with fine structures such as highly integrated circuits, semiconductor lasers, and photodetectors. Vapor phase growth, liquid phase growth, and molecular beam epitaxy are mainly used as thin film growth methods, but vapor growth has the advantage of direct growth from source gas to crystal substrates, making it easier to mass-produce. is the best.

In the conventional vapor phase growth method, a raw material gas and a transport gas are introduced into a reaction tube through a gas introduction section, and a crystal substrate is placed in the middle and heated by high frequency or the like. A part of the raw material gas undergoes a chemical reaction on and near the crystal substrate, and grows epitaxially on the crystal substrate. After passing over the crystal substrate, the unreacted raw material gas adheres to the wall of the reaction tube. The gas is discharged from the reaction tube gas outlet through the Q reaction tube, passes through a filter that captures reaction products, and is sent to the raw material gas processing tower.

However, when a conventional reaction tube is used, the gas that contributes to the growth reaction is a part of the total flow rate, and a portion of the residual gas is produced downstream of the reaction tube as a product of various chemical reactions or in the form of raw material gas. It also adheres to reaction tube walls and exhaust system piping. Particularly in the case of organometallic vapor phase growth of gallium arsenide, etc., poisonous arsine is used as a raw material for group III atoms, but some of the arsine gas that does not decompose is deposited as arsine in reaction tubes and exhaust system piping, and also forms pulp. Gas may stagnate in nearby dead ends, etc., and toxic gas may be released outside the reaction tube when substrates are put in or taken out of the reaction tube, potentially endangering the health of workers. Therefore, a substrate exchange chamber is installed at the outlet of the reaction tube to prevent toxic gases from being released into the atmosphere, but in doing so, consideration must be given to the opening and closing part between the reaction tube and the substrate exchange chamber and the airtightness of the substrate exchange chamber. (Objective of the Invention) The object of the present invention is to solve the above problems by devising the structure of the reaction system and to provide a relatively simple method. An object of the present invention is to provide a vapor phase growth apparatus that removes unreacted raw material gas gold.

(Structure of the Invention) In a vapor phase growth apparatus that performs crystal growth by supplying a source gas into a vapor phase growth reaction tube, a contact area with the source gas is large in a downstream portion of a crystal substrate placed in the vapor phase growth reaction tube. There is obtained a vapor phase growth apparatus characterized in that (1) a heating auxiliary component is provided, and a heating means is provided outside the reaction tube in which the heating auxiliary component is provided.

(Detailed explanation of forming #) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a partially sectional side view for explaining the entire principle of the vapor phase growth apparatus of the present invention. In the figure, inside a horizontal quartz reaction tube (hereinafter simply referred to as a reaction tube) 1, a gallium arsenide crystal substrate (hereinafter simply referred to as a crystal substrate) 2 is placed on a graphite support stand (hereinafter simply referred to as a support stand) 4.
is arranged, and a heating auxiliary part 5 made of carbon is arranged downstream of the crystal substrate 2 to decompose unreacted gas. Two high frequency coils are provided outside the neck reaction tube 1 as heating means. Upstream high frequency coil 3Fi8 crystal substrate 2
The high frequency coil 6 on the downstream side heats the heating auxiliary part 5t for decomposing unreacted gas. The heating auxiliary part 5 is provided with a plurality of thin plates made of graphite perpendicular to the direction of the gas flow in order to increase the contact area with the unreacted gas. For example, hydrogen is supplied through the gas inlet of the reaction tube 1, reaches the crystal substrate, and part of it reacts and precipitates as crystals, and unreacted gas and hydrogen reach the heating auxiliary part 5 and pass through the heating auxiliary part 5. Flows downstream. At this time, the unreacted gas, especially the poisonous arsine, is heated by the heating auxiliary part 5 and thermally decomposed into arsenic molecules. It is also exhausted from the reaction tube and captured by a filter installed in the exhaust system. As a result, it is possible to suppress the residual arsine in the reaction tube and exhaust system, which is seen in conventional devices that discharge unreacted gas without the need for heating auxiliary parts 5 (Example) Next, FIG. 2 shows the present invention. 1 is a partially cross-sectional side view showing an embodiment of a vapor phase growth apparatus in FIG. 1. In the same figure, the same components as in FIG. Furthermore, a quartz inner tube 7 is provided for gas flow control. The vicinity of the crystal substrate is heated through the support stand 4 by the high frequency coil 3 so that the normal growth temperature is maintained at 550°C to 750°C. The heating auxiliary part 5 is made of graphite and unreacted gas is heated. A thinner plate made of graphite is provided to increase the contact area. Further, in order to prevent thermal effects on the crystal, the crystal substrate is placed at a distance of 15 mm from the crystal substrate, and is maintained at a temperature of 800 to 1000 DEG C. by a high frequency coil 6. Further, the pressure inside the reaction tube is maintained at 01 atm. Source gases such as trimethyl gallium, arsine, and transport gases such as hydrogen are supplied through the gas supply port 8 at the upstream portion of the reaction tube, and exhaust gas is exhausted from the gas discharge port 9. be done. In such a state, trimethyl gallium and arsine guided into the reaction tube 1 reach the crystal substrate 2, cause a thermal decomposition reaction, and form gallium arsenide to evittally grow, and the unreacted gas reaches the heating auxiliary part 5 and is decomposed. .

(Effects of the Invention) As a result of experiments using the vapor phase growth apparatus of this embodiment, it was found that no arsine remained or was generated after the reaction, as would be the case without the heating auxiliary component 5. 0 without limiting the invention, i.e.
Although the example is given for the epitaxial growth of a gallium arsenide crystal substrate, other crystal substrates may be used, and the structure such as the shape of the heating auxiliary component may be arbitrarily changed to control the gas flow. Also, the heating method is not limited to high frequency coils.

As is clear from the above explanation, according to the vapor phase growth apparatus of the present invention, unreacted gas can be thermally decomposed by simple structural changes within the reaction tube, and therefore there is a possibility that the human body of the worker may be in danger. The effect of eliminating

[Brief explanation of drawings]

Fig. 1 is a partially sectional side view for explaining the principle of the vapor phase growth apparatus of the present invention, and Fig. 2 is a partially sectional side view showing an embodiment of the vapor phase growth apparatus of the present invention. In, 1...
・Horizontal quartz reaction tube, 2...Gallium arsenide crystal substrate, 3
... High-frequency coil for substrate heating, 4. Graphite support stand, ... Heating auxiliary parts for unreacted gas decomposition, 6.
...High frequency coil for heating the heating auxiliary parts, 7...Quartz inner tube, 8...Gas supply port, 9...Gas discharge port. Figure 1 Figure 2 ＾ 43/ ? 7

Claims (1)

[Claims] In a vapor phase growth apparatus that performs crystal growth by supplying a source gas into a vapor phase growth reaction tube, heating assistance is provided at the downstream portion of a crystal substrate placed in the vapor phase growth reaction tube to increase the contact area with the source gas. What is claimed is: 1. A vapor phase growth apparatus characterized in that a heating means is provided outside the reaction tube in which the heating auxiliary part is provided.