JPS62171115A - Reaction tube of vapor growth device - Google Patents

Abstract

PURPOSE:To suppress contamination within a reaction tube by inserting a reaction gas supply tube from the one end of reaction tube up to the part near to the susceptor, providing a purge gas supply port to the outer end and coupling a gas exhaust port to the space between the reaction gas supply tube and internal wall of said reaction tube. CONSTITUTION:When the reaction gas is supplied from a reaction gas supply tube 8 into a reaction tube 1, simultaneously the purge gas is supplied from a purge gas supply port 9 and the gas is exhausted from a gas exhaust port 11, the non-decomposed reaction gas not used for formation of thin film passes on the substrate 7 and flows upward in the space 10 with the purge gas, passes the gas exhaust port 11 and is exhausted to the outside of reaction tube 1. Thereby, the non-decomposed reaction gas not used for formation of a thin film does not pass the periphery of susceptor heated in the course of exhaustion. Accordingly, non-volatile product generated by thermal decomposition of non-decomposed reaction gas included in the exhaust gas is adhered to the internal wall of reaction tube ranged from the region near the susceptor to the down-stream, thereby preventing contamination of internal wall of the reaction tube. The single-sided flow of purge gas and exhaust gas in the reaction tube 1 can be prevented by providing the purge gas supply port 9 and gas exhaust port 11 with an equal interval.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a reaction system in a vapor phase growth apparatus that suppresses thermal decomposition of a reaction gas that does not contribute to growth in vapor phase growth, and reduces contamination in a reactor. Regarding pipes.

[Conventional technology]

To explain a method for growing semiconductor thin films etc. by vapor phase growth using thermal decomposition of a reaction gas, using a vertical reaction tube as an example, as shown in FIG. A suitable reaction gas (or vapor) containing the elements constituting the thin film to be grown is introduced into the reaction tube 1 through the reaction gas supply pipe 4 connected to the upper end 2, and this reaction gas is fed into the reaction tube 1. The reaction gas is pyrolyzed on the surface of or near the substrate 7, and the liberated elements or The molecules are bonded to the surface of the substrate 7 to form a thin film. On the other hand, undecomposed reaction gases that do not participate in thin film formation and byproducts (gases or nonvolatile products) generated from thermal decomposition of reaction gases
The gas passes around the susceptor 6 and is exhausted from the gas outlet 5 connected to the lower end 8 of the reaction tube 1.

[Problems that the invention attempts to solve]

However, in the vapor phase growth method that utilizes thermal decomposition of a reactive gas, a portion of the reactive gas introduced into the reactor is thermally decomposed on the substrate and contributes to thin film formation, but a considerable amount of the remaining gas is thermally decomposed on the substrate. A proportion of the reactant gas passes over the substrate undecomposed,
In the conventional method described above, a large amount of undecomposed reaction gas that does not contribute to thin film formation passes between the outer periphery of the susceptor 6 heated to a high temperature and the inner wall of the reaction tube 1 because it is guided toward the gas outlet. However, at this time, much of the undecomposed reaction gas is thermally decomposed, and the resulting nonvolatile products adhere to the inner wall of the reaction tube 1 from the vicinity of the susceptor 6 to the downstream thereof, contaminating the inside of the tube, and thus preventing the formation of a high-quality thin film. could not be grown for a long time (or many times), and the reaction tube 1 had to be washed and cleaned frequently, making it impossible to further increase the operating rate of the apparatus.

[Means for solving problems]

This invention was proposed with the aim of eliminating the above-mentioned problems.To explain the case using a vertical reaction tube as an example, as shown in FIG. A reaction gas introduction tube 8, which is connected to the reaction gas supply tube 4 at its upper end and water-cooled near the upper end, is inserted into the reaction tube 1 from the upper end 2, around the entire circumference of the reaction gas introduction tube 8. The tube 1 is inserted into the vicinity of the susceptor 6 with a space 10 formed between it and the inner wall of the reaction tube 1, and a plurality of purge gas inlets 9 are provided at the lower end 3 of the reaction tube 1, and the space 10 is filled at the upper end 2 of the reaction tube 1. A plurality of gas discharge ports 11 are connected, and in this structure, the diameter of the surface of the susceptor 6 on which the substrate 7 is mounted is larger than the diameter of the reaction gas discharge port at the lower end of the reaction gas introduction tube 8, and the surface reacts with this surface. The distance from the lower end of the gas introduction pipe 8 is approximately equal at any lower end.

[For production]

In this way, a reaction gas is introduced into the reaction tube 1 through the reaction gas inlet tube 8, a purge gas is simultaneously introduced through the purge gas inlet 9, and the gas is exhausted through the gas outlet 11. After the reaction gas passes over the substrate 7, it flows upward through the space 10 together with the purge gas and is exhausted to the outside of the reaction tube 1 through the gas outlet 11, so that undecomposed reaction gas that did not contribute to thin film formation is exhausted. Therefore, the non-volatile products generated by thermal decomposition of the undecomposed reaction gas in the exhaust gas adhere to the inner wall of the reaction tube from near the susceptor to downstream. This prevents the inside of the reaction tube from becoming contaminated.

Here, purge gas inlet 9 and gas outlet ・11
By providing these at approximately equal intervals in the lower end 3 and upper end 2 of the reaction tube 1, it is possible to prevent one-sided flow of the purge gas and exhaust gas within the reaction tube 1. In addition, the diameter of the surface of the susceptor 6 on which the substrate 7 is attached should be larger than the opening diameter of the reactive gas discharge port at the lower end of the reactive gas inlet tube 8, and the distance between this surface and the lower end of the reactive gas inlet tube 8. By making them equal at all lower ends and maintaining an appropriate distance, the purge gas can be prevented from flowing into the reaction gas introduction tube 8, and the reaction gas can be connected between the surface of the susceptor 6 on which the substrate 7 is mounted and the lower end of the reaction gas introduction tube 8. The reaction gas can be uniformly flowed out of the reaction gas introduction pipe 8 through the gap. Furthermore, by water-cooling the portion of the reaction gas introduction pipe 8 that is close to the susceptor 6, thermal decomposition of the reaction gas in this portion can be prevented.

〔Example〕

FIG. 2 shows an example of an apparatus using a vertical reaction tube as a reactor.

Reference numeral 1 in the figure is a cylindrical reaction tube made of quartz, and a reaction gas 18 (
For example, a mixed gas of (CHa)sGa and AsHs)
A cylindrical reaction gas introduction tube 8 made of quartz that guides the reaction gas to the vicinity of the substrate 7 mounted on the susceptor 6 is concentrically surrounded by the reaction tube 1 on its outer periphery, and the inner wall of the reaction tube 1 and the reaction gas introduction tube An annular space 10 is created between the outer peripheries of 8. The outer periphery of the reaction tube 1 and the outer periphery of the lower end of the reaction gas introduction tube 8 close to the susceptor 6 are each covered with a water jacket 14 for cooling. and reaction gas introduction pipe 8
It is connected by a cooling water supply pipe 15 and a drain pipe 16, and is integrated.

The upper end 2 of the reaction tube 1 includes a reaction gas supply pipe 4 inserted into the axial center of the reaction gas introduction pipe 8, and a plurality of gas exhaust ports 11 connected to the upper end of the annular space 10 at approximately equal intervals. The other end of the gas exhaust port is connected to a space 12 that serves as a passage for exhaust gas, the gas exhaust pipe 5 is connected to the space 12 and guides the exhaust gas to the exhaust device, and the joint interface with the reaction tube 1 is hermetically sealed. It is constituted by O'J rings 21a and 21b that stop.

The lower end 3 of the reaction tube 1 is filled with purge gas 19 (for example, H2).
A purge gas supply pipe 17 for supplying purge gas, an annular space 13 to which the purge gas supply pipe 17 is connected, a plurality of purge gas inlets 9 connected at approximately equal intervals inside the space 18, and an airtight joint interface with the reaction tube 1. It is constituted by an O-ring 21c for sealing.

A cylindrical susceptor 6 made of graphite that is heated by induction by an RF coil 24 is inserted into the axial center of the reaction tube 1 through the lower end 3 of the reaction tube 1, and the lower end 30 is inserted into the axial center of the reaction tube 1 by an O-ring 21d. The susceptor is held and its vertical position is adjusted by a hermetically sealed susceptor holding shaft 23.

The inner wall of the reaction tube 1 is provided with an annular knot 22 that surrounds the upper end of the side surface of the susceptor 6 and narrows the purge gas passage.

The opening diameter of the reactive gas discharge port at the lower end of the reactive gas introduction pipe 8 is:
smaller than the diameter of the upper end surface of the susceptor 6 on which the substrate 7 is attached;
Moreover, the opening surface thereof is parallel to the upper end surface of the susceptor 6.

〔effect〕

As described above, according to the present invention, the reaction gas is supplied onto the substrate through the reaction gas introduction tube inserted from one end of the reaction tube to the vicinity of the susceptor in the reaction tube, and the purge gas is introduced from the other end of the reaction tube to the susceptor side. The reaction gas is supplied from the direction opposite to the direction in which the reaction gas is supplied, and is exhausted from one end of the reaction tube into which the reaction gas introduction tube is inserted through the space between the reaction gas introduction tube and the inner wall of the reaction tube. After the reaction gas passes over the substrate, the gas flow direction is reversed and the reaction gas is exhausted without passing around the heated susceptor along with the purge gas, resulting from the thermal decomposition of undecomposed reaction gases that did not contribute to thin film formation. Adhesion of non-volatile products to the inner wall of the reaction tube is suppressed.

As a result, contamination inside the reaction tube can be suppressed, making it possible to lengthen the cleaning cycle of the reaction tube.Therefore, a stable growth reaction can be expected over a long period of time, increasing the operating rate of the apparatus.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of the device of the present invention, and FIG.
The figure is a sectional view showing the main parts of one embodiment, and FIG. 3 is a diagram showing a conventional vapor phase growth apparatus. 1101 reaction tube, 2. -0 reaction tube upper end, 3-m-reaction tube lower end, 4-m-reaction gas supply pipe, 5-.-gas discharge pipe,
61. -Susceptor, 70. 1 board, 8-m-reaction gas inlet pipe, 9-m-purge gas inlet, 10.12.13-
- Annular space, 11-- Gas outlet, 14-111 water jacket, 15-m- Cooling water supply pipe, 16--
- Cooling water drain pipe, 17-- Barge gas supply pipe, 18-
-- Reaction i Su, 19-m-vergicus, 2゜-m-
Exhaust gas, 21 a, 2 l b, 21 c,
21 d---O-ring, 22-m-annular node, 2
3-0-susceptor holding shaft, 24-- RF-y illumination,
3o, - flow of reactant gas, 31 +++ flow of purge gas. Mouth “0 box”

Claims (5)

[Claims] (1) A susceptor heated by an appropriate method is housed inside the susceptor, and a reaction gas is blown onto a substrate mounted on the susceptor to grow a thin film on the substrate. The reaction tube is a cylindrical reaction tube, and a reaction gas introduction tube is inserted into the reaction tube from one end of the reaction tube, and a space is formed between the reaction gas introduction tube and the inner wall of the reaction tube around the entire circumference of the reaction tube. A purge gas (gas inert to the growth reaction) inlet is provided at the other end of the reaction tube, and at one end of the reaction tube to which the reaction gas inlet tube is connected, the A reaction tube for a vapor phase growth apparatus, characterized in that a gas outlet is connected to the space created between the outer periphery of the reaction gas introduction tube and the inner wall of the reaction tube. (2) The diameter of the surface of the susceptor on which the substrate is attached is larger than the diameter of the reactive gas discharge port at the terminal end of the reaction gas introduction tube, and the surface of the susceptor on which the substrate is attached and the terminal end of the reaction gas introduction tube. Claim (1) characterized in that the distance from
Reaction tube of the vapor phase growth apparatus described in . (3) The purge gas inlet and the gas outlet are
2. The reaction tube of a vapor phase growth apparatus according to claim 2, wherein a plurality of reaction tubes are provided at substantially the same intervals at each end of the reaction tube. (4) A reaction tube for a vapor phase growth apparatus according to claim (3), characterized in that the reaction gas introduction tube can be water-cooled. (5) The reaction tube of the vapor phase growth apparatus is a vertical reaction tube, and the reaction gas introduction tube is inserted into the reaction tube from the upper end of the reaction tube, and the purge gas introduction port is inserted into the lower end of the reaction tube. 4. A reaction tube for a vapor phase growth apparatus according to claim (4), characterized in that the gas discharge port is provided at an upper end of the reaction tube.