JPH02145767A - Method and device for cleaning vapor-growth reaction furnace - Google Patents

Abstract

PURPOSE:To economically, easily, and perfectly clean a reaction furnace in a short time by cleaning the furnace used for the vapor growth of silicon, etc., until the pH of a cleaning liq. reaches a specified value, then cleaning the furnace with the hydrogen peroxide kept at a specified concn., and further cleaning the furnace with pure water. CONSTITUTION:A gaseous mixture of SiH4 and a silicon halide or a germanium halide or a silicon halide is pyrolyzed, and reduced with hydrogen to produce Si or an Si-Ge alloy on a carrier. The reaction furnace body 1 after vapor growth is placed above a cleaning device 2 through a base flange 3. A rotary brush 9 provided with brushes 10 is then rotated by injecting a cleaning liq. from a nozzle 7 to clean off the deposit on the inner wall of the furnace. Water is firstly used as the cleaning liq., and the furnace is cleaned until the pH of the liq. after cleaning reaches 4-7. The furnace is then cleaned using >=2vol.% H2O2. As a result, the polymer firmly attached to the wall is completely decomposed, and removed. The furnace is then cleaned with pure water, and dried. By this method, the inside of the reaction furnace is perfectly cleaned in a short time without the furnace being corroded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to the production of a gaseous mixture of monosilane and silicon halide, a gaseous mixture of monosilane and germanium halide, or silicon halide onto a carrier by a vapor phase growth method. The present invention relates to a method and apparatus for cleaning the inner wall of a reactor for vapor phase growth in which silicon or silicon-germanium alloy is deposited and manufactured.

[Prior Art] For example, in cleaning a reactor for producing polycrystalline silicon, as disclosed in Japanese Patent Publication No. 63-27287, cleaning is performed using a combination of hydrogen fluoride aqueous solution or sodium hydroxide aqueous solution and pure water. A method or an apparatus thereof, and a combination thereof with gas etching of the inner wall of the furnace using chlorine gas, or a method in which deposits on the inner wall of the furnace are hydrolyzed using air containing water vapor or an inert gas, and the generated hydrogen chloride does not condense. There is a cleaning method or device that discharges the solids from the furnace or removes the solids adhering to the inside wall of the furnace using an inert gas jet.

[Problems to be Solved by the Invention] However, according to such a method or apparatus, the metal reactor and cleaning equipment are corroded by the hydrogen fluoride and sodium hydroxide used in the cleaning liquid, causing severe damage. It is not economical because it reduces the service life of the equipment. Further, even if gas etching is used in combination or an inert gas jet is used, the accompanying equipment becomes large-scale, and the process becomes complicated and takes a lot of time.

[Means for Solving the Problems] The present invention has been made to solve the problems of the above-mentioned cleaning methods and cleaning equipment that have been conventionally used for vapor phase growth equipment. Cleaning of a reactor for vapor phase growth for producing silicon or silicon-germanium alloy on a carrier by thermal decomposition and hydrogen reduction reaction of a mixed gas of silicon halide, a mixed gas of monosilane and germanium halide, or silicon halide In the method, the first step is to adjust the pH of the washing solution after washing to 4.
Adjust to 7 to 7, then as the third step, 2v
The device is characterized by cleaning with 0.1% or more hydrogen peroxide, and finally, in the third step, cleaning with pure water.Furthermore, in this equipment, a brush is applied radially onto the surface of the pipe equipped with a large number of nozzles. One end of the pipe is connected to a rotary drive unit to enable the pipe to rotate, and a liquid pressure feeding mechanism for feeding liquid into the pipe is connected to the end of the pipe, so that the liquid flows through the pipe while rotating. The rotary brush is configured to be injected from a nozzle, and a mechanism that collects the liquid after being injected and circulates it again into the pipe, and the rotary brush is inserted into the reactor. It is characterized in that it is configured to clean walls. Also,
It is more efficient if the liquid pressure feeding mechanism is provided with a liquid feeding pipe having branches and valves so that liquids of different compositions can be alternately forced into the pipe.

To explain this with reference to the drawings, brushes 1oIJ<, 1 are radially cut on the surface of a pipe 21 equipped with a large number of nozzles shown at 7 in FIG. 1, which is an embodiment of the present invention. A rotary drive unit composed of a motor 8, a belt 22, and a rotary joint 23 is connected to the pipe 21 so that the pipe 21 can rotate. Furthermore, the upstream side of this pipe 21 and the rotary joint 23 are branched, and one side has a pump 12 for sending liquid into the pipe 21 and injecting it from the nozzle.
On the other hand, there is a liquid feeding mechanism composed of a liquid feeding pipe 24, which sends water into the pipe 21, and a water feeding pipe 2 for similarly injecting water.
5 are connected.

Therefore, the rotary brush 9 consisting of the pipe 21, the nozzle 7, and the brush 10 sprays liquid while rotating, and scrubs the inner wall of the reactor main body with the radial brush on the surface.

Further, this cleaning device has a mechanism for recovering the hydrogen peroxide solution after cleaning into the recovery tank 2o by adjusting the valve 13 and circulating it again into the pipe.

[Operation] When polycrystalline silicon is produced by vapor phase decomposition of monosilane, so-called amorphous silicon adheres to the inner wall of the reaction vessel. However, this can be removed relatively easily with something like a suction device. However, when using silicon halide, the inner wall of the reactor was
As described in Japanese Patent No. 3-27287, it is said that a high boiling point polymer is precipitated as a by-product, and furthermore, this polymer is difficult to remove by suction.

The present inventor has discovered that such polymers produced as by-products in gas phase decomposition reactions using halides are 2v0 in the weakly acidic to neutral range.
It was discovered that hydrogen peroxide at a concentration of 1% or more can be easily decomposed and removed, and by utilizing this effect, the present invention was completed.

[Example 1] Figures 1 and 2 show an apparatus used in an example of the present invention and equipment attached thereto. The reactor main body 1 for vapor phase growth, which had undergone the step of growing a silicon-germanium alloy, was installed on the base flange 3 of the cleaning bag ra2. After installation, the exhaust nozzle 4 was operated, and a transparent cover 5 was attached to the upper part of the vapor phase growth reactor main body 1. The valve 6 was opened and water was spouted from the nozzle 7 at a rate of 20Q1 min for 3 minutes, and by-products adhering to the inner wall surface of the furnace that were easy to fall off were first allowed to fall into the collection groove.

Next, the motor 8 was started, and the rotary brush 9 was rotated to supply water while scrubbing the inner wall surface of the furnace with the brush 10 and washing with water for 10 minutes. After confirming that the pH of the wastewater is approximately 5, close valve 6, open valve II, and turn on pump 12.
was activated, and while rotating the rotary brush 9, 5% hydrogen peroxide solution was jetted from the nozzle 7 at a rate of 15 Ω/min for 20 minutes to perform cleaning. When the cleaning condition was visually checked through the transparent cover 5, it was found that the polymer that had firmly adhered to the inner wall surface of the reactor main body had been completely decomposed and removed, so the pump 12 was stopped and the peroxidation Finished cleaning with hydrogen water.

In addition, during cleaning with hydrogen peroxide solution, the drained liquid is collected by setting the valve 13 to the recovery side and collecting the hydrogen peroxide solution in the recovery tank 2.
0 was recovered and recycled.

The valve 11 was closed, the valve 13 was turned to the drain side, the valve 6 was opened, and the inside of the reactor main body was rinsed with water for about 10 minutes, and then the motor 8 was stopped.

Close the valve 6 to stop the water, remove the reactor main body l from the base flange 3 of the cleaning device 2, and dry the dryer 1 shown in FIG.
It was installed on the base flange 15 of 4. A transparent cover 16 with air vent holes 17 in several places is attached to the reactor body l.
It was attached to the top of the.

Close the valve 18, operate the hot air generator 19, and
℃~100℃ hot air at a rate of 1.5+rr/min for 10
The mixture was poured into the reactor main body 1 for a minute and dried. During this time,
The valve 18 was opened several times to drain the water that had accumulated on the base of the dryer 14.

When the inner wall surface of the reactor main body, which had been washed and dried in this way, was observed, it was found that the adhered polymer was completely removed.

Furthermore, monosilane gas was thermally decomposed in this reactor, and the polycrystalline silicon deposited on the substrate was single-crystallized by the FZ method, and it had a specific resistance of 50ooΩ·(1). in this way,
It has been confirmed that the cleaning method and cleaning apparatus of the present invention are extremely effective in removing polymers adhering to the inner wall of a reactor for vapor phase growth when a halide is used.

In this example, the reactor used for gas phase decomposition of a mixed gas of monosilane and germanium halide was
Although the present invention was applied, it was confirmed that it can be similarly applied to a reactor used for gas phase decomposition of a mixed gas of monosilane and silicon halide, or only silicon halide.

[Effects of the Invention] According to the present invention, it is possible to completely remove the strong polymer on the inner wall of the reactor used in the gas phase decomposition reaction of halides, which could not be completely removed in the past, in a short time. Therefore, silicon by vapor phase decomposition or silicon-
The time required for the germanium alloy manufacturing process is shortened and productivity is improved.

The work environment is also good because no acid or alkali is used as the cleaning liquid. Economic efficiency is also improved because equipment corrosion is eliminated and the service life is extended.

Furthermore, since the cleaning process is simple and no large-scale cleaning equipment is required, it can be easily installed and implemented.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a cleaning device for a vapor phase growth reactor showing an embodiment of the present invention. FIG. 2 is a reference longitudinal cross-sectional view of a dryer attached to the washing device of the present invention. 1・・・・・・・・・・・・Reactor main body 2・・・・・・
・・・・・・・・・Cleaning device 3.15・・・・・・・・・
-Base flange 4...Exhaust fan 5.16...Transparent cover 6.1.
1,13.18... Valve 7...
・・・Nozzle 8・・・・・・・・・・・・・・・ 9・・・・・・・・・・・・・・・ 10・・・・・・・・・・・・ 12...・・・・・・・・・・・・ 14・・・・・・・・・・・・ 17・・・・・・・・・・・・ 19・・・・・・・・・・・・・・・ 20・・・・・・・・・・・・ 22・・・・・・・・・・・・ 23・・・・・・・・・・・・ 24・・・・・・・・・・・・・・・ 25・・・・・・・・・・・・

Claims (1)

[Claims] 1. Producing silicon or silicon germanium alloy on a carrier by thermal decomposition and hydrogen reduction reaction of a gas mixture of monosilane and silicon halide, a gas mixture of monosilane and germanium halide, or silicon halide. In the method for cleaning a reactor for vapor phase growth, a first step of cleaning until the pH of the cleaning solution after cleaning reaches 4 to 7;
1. A method for cleaning a reactor for vapor phase growth, comprising a second step of cleaning with ol% or more hydrogen peroxide, and a third step of cleaning with pure water. 2. For vapor phase growth to produce silicon or silicon-germanium alloy on a carrier by thermal decomposition and hydrogen reduction reaction of a gas mixture of monosilane and silicon halide, a gas mixture of monosilane and germanium halide, or silicon halide In a reactor cleaning device, brushes are provided radially on the surface of a pipe equipped with a large number of nozzles, one end of the pipe is connected to a rotation drive unit to enable the pipe to rotate, and liquid is further sent into the pipe. A rotary brush configured to connect a liquid pressure feeding mechanism to the end of the pipe so that the liquid is injected from the nozzle of the pipe while rotating on its own axis, and a rotary brush that collects the ejected liquid and returns it into the pipe. 1. A cleaning device for a reactor for vapor phase growth, comprising a circulating mechanism and configured to be inserted into a reactor to clean a wall of the reactor. 3. The vapor phase growth according to claim 2, characterized in that the liquid pressure feeding mechanism is provided with a liquid feeding pipe having a branched valve and is configured to be able to alternately force feed liquids of different compositions into the pipe. Reactor cleaning equipment.