JPS61166123A - Vapor growth apparatus - Google Patents

Abstract

PURPOSE:To enable to monitor the surface of a substrate at all times by a method wherein the reactive substance of the gas, to be used for vapor growth method, supplied into an internal pipe is prevented from adhering to the inner wall of a reaction pipe by the non-reaction gas running along the inner wall of the reaction pipe. CONSTITUTION:The hydrogen gas 5, which is the non-reaction gas having no relation with the growth of crystal, is supplied between a reaction pipe 3 and an internal pipe 4 from a gas feeding hole 6, and the gas 5 flows along the inner wall of the reaction pipe 3. On the other hand, the gas 7 and 8 to be used for a vapor growth method are supplied from the gas feeding holes 9 and 10 located inside the internal pipe 4 in such a manner that said gas is not flow into the space located between the reaction pipe 3 and the internal pipe 4, and the gas is subjected to thermal decomposition on the surface of a heated substrate 1, thereby enabling to grow crystals. The reaction substance generated at this time does not adhere at least to the inner wall of the reaction pipe 3 in the vicinity of the plate where the substrate 1 is placed by the action such as an air curtain of the non-reaction gas 5 flowing along the inner wall of the reaction pipe 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vapor phase growth apparatus capable of obtaining a high quality and uniform semiconductor crystal growth layer.

2. Description of the Related Art As a two-vane epitaxial growth technique for semiconductor crystals necessary for manufacturing semiconductor devices, there is a vapor phase growth method that utilizes thermal decomposition of raw material gas. For example, monosilane (SI
These methods include a silicon (Si) vapor phase epitaxy method using H, s ), and a metal organic chemical vapor deposition method (MOCVD method) for growing compound semiconductor crystals using an organic metal (alkylated compound). In any of the vapor phase growth apparatuses, a substrate is generally heated to a growth temperature, and raw material gas is thermally decomposed on the substrate surface to grow crystals.

However, the thermal decomposition reactant of the raw material gas, that is, the gas for vapor phase growth, not only forms crystals on the surface of the substrate, but also adheres to the inner wall of the surrounding reaction tube 3, as shown in FIG. For this reason, the inner wall of the reaction tube in the downstream part 31 of the gas flow from the substrate heating table 2 on which the substrate 1 is placed and heated to the growth temperature becomes dirty, causing a problem that it becomes difficult to monitor the substrate surface condition from the outside. there were. Furthermore, the attached reactants may be generated again as a gas, or may peel off as particles or flakes and adhere to the growth surface, which poses a problem of adversely affecting the quality of the grown crystal layer.

3'\- Therefore, in order to prevent the reactant of the gas for vapor phase growth from adhering to the inner wall of the reaction tube, for example, the reaction tube was made double as shown in Fig. 5, and the inner tube 41 was made detachable. A vapor phase growth method was considered (Japanese Patent Application No. 65918 (1981)). Suwachi,
An inner tube 41, which has a smaller diameter than the reaction tube 3 and can be easily attached and detached from the reaction tube 3, is inserted into the reaction tube 3. and its inner tube 41
A substrate heating table 2 on which a substrate 1 is placed is installed inside, and a gas for vapor phase growth is introduced from gas introduction pipes 42 and 43 to perform crystal growth. Therefore, the reactant of the gas for vapor phase growth is contained in the inner tube 41.
However, it does not adhere to the reaction tube 3. Therefore,
By replacing the inner tube 41 during the next crystal growth, it becomes possible to always perform crystal growth in a clean state.

Problems to be Solved by the Invention However, in such a method, the reactants of the vapor growth gas arrive at the inner wall of the inner tube 41 during crystal growth and become dirty, so that it is still necessary to Monitoring the crystal surface is difficult. Therefore, it is not possible to detect the substrate surface temperature with an infrared detector or the like or to analyze the growth layer from the row side of the reaction tubes 3. Furthermore, since the inner tube 41 is replaced for each growth, there are problems in that a large number of inner tubes are required, or the dirty inner tubes are not cleaned frequently, which is time-consuming.

Uninvented illusion: It was created with these points in mind, and it has a simple configuration, the inside of the reaction tube can always be clearly seen, and the surface condition of the substrate can be monitored even during crystal growth. It is an object of the present invention to provide a vapor phase growth apparatus that eliminates contamination of layers.

Means for solving the problems and the technical means of the present invention for solving the above problems are as follows: A substrate heating table placed inside the reaction furnace is provided on the flow side of the reaction tube from the inside diameter of the reaction tube. The non-reactive gas is provided between the reaction tube and the inner tube so that the non-reactive gas unrelated to vapor phase growth flows along the inner wall of the reaction tube. A gas supply port for the vapor phase growth gas is provided inside the inner tube to prevent the vapor phase growth gas from flowing between the reaction tube and the inner tube. It is equipped with the following.

For production The effect of this technical means is as follows.

That is, a non-reactive gas not related to vapor phase growth is supplied between the reaction tube and the inner tube, and flows out from between them along the inner wall of the reaction tube in the vicinity of the substrate installation. Therefore, the reactants of the vapor phase growth gas supplied into the inner tube are prevented from adhering to and contaminating the inner wall of the reaction tube by the non-reactive gas flowing along the inner wall of the reaction tube like an air curtain.

As a result, the inner wall of the reaction tube is not contaminated even during crystal growth.
The substrate surface can be constantly monitored.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings. In FIG. 1, a reaction tube 3 is placed on the upstream side of the gas flow from the substrate heating table 2 on which the substrate 1 is placed and heated to the growth temperature.
An inner tube 4 with a smaller inner diameter is provided. Usually made of quartz. Methods for heating the substrate 1 include high frequency heating, resistance heating, etc., but any method that allows the inside of the reaction tube to be seen may be used. In this example, vapor phase growth was performed using a high frequency heating method. Hydrogen gas 5, which is a non-reactive gas not related to crystal growth, is supplied between the reaction tube 3 and the inner tube 4 from the gas supply port 6, and flows along the inner wall of the reaction tube 3 as shown in the figure. On the other hand, the gas for vapor phase growth 7.8 is supplied from gas supply ports 9, 1o inside the inner tube 4 so as not to flow between the reaction tube 3 and the inner tube 4. The vapor growth gas supplied into the inner tube 4 undergoes a thermal decomposition reaction on the heated surface of the substrate 1, causing crystal growth. The reactants generated at this time are prevented from adhering to the inner wall of the reaction tube 3 at least near where the substrate 1 is placed due to various effects of the air curtain caused by the non-reactive gas 5 flowing along the inner wall of the reaction tube 3. In other words, the inner wall of the reaction tube 3 is not contaminated in the region until the non-reactive gas 5 and the gas for vapor phase growth after the thermal decomposition reaction are mixed.

As a result, the surface of the substrate 1 can be constantly monitored even during crystal growth. Therefore, it is possible to detect the temperature of the surface of the substrate 1 with an infrared detector or the like. Furthermore, reaction tube 3
It is also possible to prevent contamination of the substrate growth layer due to deposits.

Note that the inner tube 4 may have a shape in which the upstream portion of the gas flow is closed, as shown in FIG. 2. All the gas in the reaction tube 3 is exhausted from the exhaust pipe 11.

FIG. 3 is a schematic diagram of a gas system of a metal organic vapor phase growth apparatus having a reactor 3 having the above structure. 21 is a high-pressure cylinder of hydrogen gas, which is a non-reactive gas and a carrier gas;
22 is a mass flow for flow rate control, 23 is a high pressure cylinder for vapor phase growth gas, and 24 is a container containing an organic metal. 2
5 is a high frequency coil, 26 is a high frequency generator, and 27 is an exhaust gas treatment device.

In the above explanation, a metal organic vapor phase growth apparatus has been described, but the present invention can also be applied to a normal vapor phase growth apparatus. Although the non-reactive gas is shown to be the same as the carrier gas, it may be a different gas or a gas unrelated to crystal growth (for example, N2 gas).

Effects of the Invention As mentioned above, according to the present invention, the adhesion of reactants to the inner wall of the reaction tube, which is one of the difficulties in vapor phase growth, can be prevented.
This eliminates the problem of not being able to see the inside of the reaction tube and contamination of the growth layer, and provides high-quality crystals, which will be extremely useful in vapor phase growth in the future.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the reaction tube section of a vapor phase growth apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of the reaction tube section of a vapor phase growth apparatus according to another embodiment of the present invention. 3 is a gas system diagram of a vapor phase growth apparatus according to an embodiment of the present invention; FIG. 4 is a fil-m cross-sectional schematic diagram of a reaction tube section of a conventional vapor phase growth apparatus;
FIG. 5 is a schematic cross-sectional view of the reaction tube section of a conventional double reaction tube type vapor phase growth apparatus. 2...Substrate heating table, 3...Reaction tube, 4...
...Inner tube, 5...Non-reactive gas, 6,9.1
0... Gas supply port, 7.8... Gas for vapor phase growth.

Claims (1)

[Claims] An inner tube having an outer diameter smaller than the inner diameter of the reaction tube is provided on the upstream side of the gas flow from the substrate heating stand placed inside the reaction tube, and non-reactive gases not related to vapor phase growth are contained in the reaction tube. A gas supply port for the non-reactive gas is provided between the reaction tube and the inner tube so that the gas flows along the inner wall, so that the gas for vapor phase growth does not flow between the reaction tube and the inner tube. A vapor phase growth apparatus characterized in that a gas supply port for the vapor phase growth gas is provided inside the inner tube.