JPS6054919B2 - low pressure reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-pressure reactor and a reaction processing method using the same, such as a method for manufacturing a semiconductor device using a low-pressure reactor.

As shown in FIG. 1, the low-pressure reactor is equipped with a cylindrical reaction tube 2 made of quartz glass installed laterally, into which a Si wafer 5 is supported and inserted into a susceptor 4, and the wafer 5 undergoes vapor phase growth. (Si epitaxial, Si polycrystalline, etc.) can be considered.

However, in such a low-pressure reactor, reactants tend to adhere to the inner wall of the reaction tube 2, especially monosilane (
When used as a reaction gas with SiH,), the decomposition temperature is as low as 400°C or less, so the adhesion is particularly severe.
It was found that this caused variations in the thickness of the grown layer along the flow direction of the reactant gas. On the other hand, when a rectangular reaction tube is used as the reaction tube, it has been found that it is not suitable for low-pressure reactions because of its low pressure resistance. The present invention aims to eliminate these drawbacks of the reactor, and its purpose is to provide a low-pressure reactor with less variation in the thickness of the vapor-phase growth layer and with less contamination in the reaction tube. be.

Another object of the present invention is to provide a low-pressure epitaxial device in which autodoping is reduced in the case of epitaxial growth. The gist of the present invention for achieving such objects is to provide an inner tube that houses the object to be processed and into which a reaction gas is introduced, an outer tube that surrounds the inner tube, and a heating source that is present outside the outer tube. A low-pressure reaction apparatus is characterized in that the object to be processed is treated by flowing a gas between the inner tube and the outer tube and introducing a reaction gas into the inner tube.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a partially omitted perspective view of the low-pressure reactor of the present invention, and FIG. 3 is a view of FIG. 2 viewed from the direction of the arrow.

This low-pressure reactor 10 has a circular or elliptical cylindrical protection tube 11 made of quartz glass, which is placed horizontally, and inside this is a prismatic reaction tube made of quartz glass and formed into a rectangular tube shape. The tube 12 was inserted along the central axis of the protective tube 11, a high frequency coil (RF coil) 13 for high frequency induction heating was wound around the outside of the rectangular reaction tube 12, and the inside of the tube 12 was coated with silicon carbide SiC. A susceptor 14 made by Graphai Co., Ltd. is placed thereon, and a Si wafer 15 is placed thereon.Then, while a carrier gas such as carbon dioxide or N2 is flowing into the rectangular reaction tube 12, a vacuum pump (not shown) is used to reduce the The pressure is maintained at a constant low pressure in the range of ~300T'0m.Also, a cooling gas such as carbon dioxide or N2 is flowed between the rectangular reaction tube 12 and the protection tube 11 while maintaining the pressure at a low level at the same time. Balance the pressure inside and outside the reaction tube 12 to prevent destruction of the reaction tube 12. In other words,
The pressure between the inner and outer tubes is equal to or slightly higher than that of the reaction tube 12, for example, about 1.1 to 2 times. Then, the susceptor 14 is heated to a predetermined temperature (a constant temperature in the range of approximately 500 to 1200°C depending on the reaction purpose and reaction gas) by high-frequency induction heating of the high-frequency coil (RF coil) 13, and the reaction tube 12 The reaction is carried out under low pressure with the reaction gas flowing inside.
A vapor layer growth layer is formed on the Sf wafer 15.

The above-mentioned reactive gas is, for example, N2+SiH when growing Si polycrystals on a Si wafer to be processed.
4, when growing Si single crystal, H2 + Si crosspiece +
Dopower (PH3, B5H6, etc.) is used.

Note that SiCl4, SiHCl3, Si
H2Cl2 etc. may also be used. Further, the high frequency coil (RF coil) 13 may be wound on the outside of the protective tube 11, and instead of this high frequency coil (RF coil) 13, a structure may be used in which heating is performed using a lamp. In addition, the cooling gas is H2
, H2, vapors such as H2Ol Freon may be used, and the materials to be grown are not only Si but also Sl3N4, SiO2,
Compounds such as Af2O3 (CVD grown) may also be used.

Compound semiconductors such as GaA3 and GaP (especially those using an organic compound as a reactive gas) may be grown. In the above embodiment, the outer protective tube 11 is made of quartz glass, but it may also be a metal tube provided with a temperature measurement window (not shown).

Among such metal tubes, rectangular tubes can be used because of their high pressure resistance, and if the device is large, metal tubes have the advantage of being easier to manufacture. FIG. 4 shows another embodiment of the present invention,
Both the reaction tube 12 and the protection tube 11 are made of quartz glass.
These are welded and integrated, and a high frequency coil (RF coil) 13 is wound around the outside of the protective tube 11. FIGS. 5 and 6 show still other embodiments of the present invention.

In FIG. 5, the reaction tube 12 and the protection tube 11 are both made of quartz glass and welded together, and the reaction gas supply chamber 16, reaction chamber 17,
It is divided into an exhaust gas discharge chamber 18 and a cooling chamber 19. A gas distributor 20 made of a porous plate of quartz glass is provided between the reaction gas supply chamber 16 and the reaction chamber 17, so that the reaction gas flows uniformly from a direction perpendicular to the rows of wafers 15. This situation is illustrated in the plan view of FIG. 6, but a perforated quartz glass plate 21 is provided between the reaction chamber 17 and the exhaust gas discharge chamber 18, and the exhaust gas after the reaction can be quickly removed by a vacuum pump. It is a product that is discharged and manufactured. In this case, since the reaction gas flows uniformly to each wafer 15, variations in the growth layer are greatly reduced. As shown in the various examples above, the low pressure reactor of the present invention has the following features.

The reaction tube 12 has a double structure of the reaction tube 12 and the protection tube 11, and the low pressure between them is balanced with the low pressure inside the reaction tube, so that the reaction tube 12 can have a rectangular structure made of quartz glass with low pressure resistance. In addition, since the cooling gas flows between the reaction tube 12 and the protection tube 11, it is possible to prevent the reactants from adhering to the inner wall of the reaction tube 12, and the thickness variation in the flow direction of the reaction gas is reduced. The reaction tube 12 is made of quartz glass and has a simple structure, so the variation in the reaction gas in the perpendicular direction is reduced.
Numerous benefits can be obtained, including a reactor with less contamination from inside the device. Furthermore, when the present invention is applied to a low-pressure epitaxial device, in addition to the above-mentioned effects, autodoping is reduced due to low-pressure growth. Furthermore, when the present invention is applied to a vertical reactor as shown in FIG. 7, in addition to the above advantages, the pressure inside the inner tube can be lowered.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the low-pressure reactor, FIG. 2 is a partially omitted perspective view of the low-pressure reactor of the present invention, FIG. 3 is an enlarged view of FIG. 2 viewed in the direction of the arrow, and FIGS. FIG. 7 is a diagram showing another embodiment of the reaction apparatus of the present invention. 2...Reaction tube, 4...Susceptor, 5.
... Si wafer, 10 ... Low pressure reaction device, 11 ... Cylindrical protection tube, 12 ... Square reaction tube, 13 ... High frequency Coil (RF coil), 14...susceptor, 15...Si
Wafer, 16...Reaction gas supply chamber, 17...
...Reaction chamber, 18...Exhaust gas discharge chamber, 1
9... Cooling room, 20... Gas distributor,
21...Perforated board, 22...●●●Belgear.

Claims (1)

[Claims] 1 An inner tube that houses the object to be processed and into which a reaction gas is introduced, an outer tube that surrounds the inner tube, and a heat source that is present outside the outer tube, and has a A low-pressure reaction apparatus characterized in that the object to be processed is processed by flowing gas through the inner tube and introducing a reaction gas into the inner tube.