JPS6128371B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reduced pressure type vapor phase growth apparatus, and more particularly to a reduced pressure type vapor phase growth apparatus equipped with a cleaning mechanism inside a reaction tube.

A conventional reduced pressure type vapor phase growth apparatus is shown in FIG. That is, in this FIG. 1, 1 is a reaction tube, 2 is a jig that is placed and held in the reaction tube 1 with a semiconductor substrate 3 placed thereon, and 4 is a heating coil arranged around the reaction tube 1. , 5 is an exhaust pipe connected to an exhaust system for depressurizing and exhausting the inside of the reaction tube 1, and 6 is a gas introduction pipe for introducing a reaction gas into the reaction tube 1.

The operation of this conventional configuration involves heating the inside of the reaction tube 1 with the heating coil 4 to a temperature at which reaction products can be sufficiently formed, and then mounting the semiconductor substrate 3 mounted and held on the jig 2 in the reaction tube 1. After that, the inside of the pipe is evacuated through the exhaust pipe 5, and the gas introduction pipe 6 is
A more reactive gas is introduced into the tube, and a thin film of reaction products is formed on the substrate surface under a predetermined reduced pressure.

For example, when monosilane (SiH ₄ ) and nitrogen (N ₂ ) are used as reactive gases, polycrystalline silicon can be obtained, and when dichlorosilane (SiH ₂ Cl ₂ ) and ammonia (NH ₃ ) are used, silicon nitride can be obtained. It will be done. However, when levers are generated, the products are deposited not only on the substrate surface but also on the tube wall of the reaction tube 1 and the surface of the jig 2 at the same time, and once these deposits are formed, the subsequent reactions This will interfere with normal membrane formation during the process. Therefore, it is necessary to promptly remove these extra deposits, but since conventional equipment itself does not have this function,
Once the reaction tube was removed, it was inconvenient that the jig had to be thoroughly washed with a solution such as hydrofluoric acid.

This invention is an attempt to improve such drawbacks of the conventional technology, by providing a cleaning plasma generation chamber in the gas pipe that is the front stage of the reaction tube, so that the reaction tube can be cleaned with generated gas plasma without removing it. This is what I did.

Hereinafter, one embodiment of the inventive device will be described in detail with reference to FIG. 2.

In this FIG. 2, the same reference numerals as those in FIG. In addition to disposing the electrode 8, a cleaning reaction gas supply pipe 10 is provided.
and a pipe switching valve 11,
The electrode 8 for plasma generation may be either a capacitive type or an inductive type.
Note that 13 is a plasma shielding plate.

Therefore, in this embodiment as well, film formation on the substrate surface is carried out in exactly the same manner as in the conventional example described above, but at this time, valve 11 is closed and valve 12 is left open. When cleaning the inside of reaction tube 1,
On the contrary, the valve 11 is opened, the valve 12 is closed, and a cleaning gas such as CF ₄ gas is supplied from the supply pipe 10 into the plasma generation chamber 7, and
The output of the RF oscillator 9 is applied to the electrode 8 to generate gas plasma, which is sent from the gas introduction tube 6 into the reaction tube 1 under high temperature (600 to 800°C) and reduced pressure (0.1 to 0.5 Torr). By causing a reaction with plasma radicals, deposits such as polycrystalline silicon and silicon nitride deposited on the tube wall are removed, and the removed deposits are discharged to the outside from the exhaust pipe 5. By continuing this washing operation for a predetermined period of time, the inside of the reaction tube 1 can be sufficiently washed.

Further, in the above embodiment, the case where polycrystalline silicon or silicon nitride was deposited was described, but even when silicon dioxide, which is generated due to the contamination of oxygen or moisture due to leakage from pipes, is deposited on the pipe wall, A reactive gas that becomes a plasma radical that reacts with this silicon dioxide, e.g.
This can be easily removed by using C ₃ F ₈ gas.

As described in detail above, according to the present invention, a plasma generation chamber is provided in the gas introduction tube at the front stage of the reaction tube, and a cleaning gas is supplied to the plasma generation chamber, so that the gas plasma causes deposits in the reaction tube. Since the reaction products removed by the reaction tubes are removed, there is no need to remove and clean the reaction tubes one by one, which improves the operating efficiency of the equipment. This is what can be obtained under the

[Brief explanation of the drawing]

Figure 1 shows a conventional vacuum-type vapor phase growth apparatus.
Further, FIG. 2 is a schematic diagram of a reduced pressure type vapor phase growth apparatus to which an embodiment of the present invention is applied. DESCRIPTION OF SYMBOLS 1... Reaction tube, 2... Jig, 3... Semiconductor substrate, 4... Heating coil, 5... Exhaust pipe, 6... Gas introduction pipe, 7... Plasma generation chamber, 8... Electrode,
9...RF oscillator, 10...Cleaning gas supply pipe.

Claims (1)

[Claims] 1. In a reduced pressure vapor phase growth apparatus in which a gas introduction pipe for introducing a reaction gas into the tube and an exhaust pipe of an exhaust system for evacuation of the inside of the tube are connected to a reaction tube having a heating means, the gas introduction tube is connected to a reaction tube having heating means. A cleaning plasma generation chamber is provided, and a cleaning reaction gas is supplied to the plasma generation chamber so that reaction products deposited in the reaction tube are removed by gas plasma generated from the plasma generation chamber. A reduced pressure type vapor phase growth apparatus characterized by the following.