JPS61136677A - Apparatus for producing silicon - Google Patents

Abstract

PURPOSE:To remove efficiently pulverous powder silicon with simple constitution by capturing the pulverous powder silicon by-produced in a reaction chamber by a dust trap, introducing the same into an oxidizing means and subjecting the powder to a discharge treatment with a wet process dust collector. CONSTITUTION:A gaseous raw material contg. silicon is cracked in the reaction chamber 1 to deposit silicon on a substrate. The unreacted gaseous raw material and gaseous by-product remaining in the chamber 1 are introduced by an evacuation device 2 into the oxidizing means 3. The pulverous powder silicon by- produced in the chamber 1 is captured by the dust trap 10 provided in the mid-way of the discharge route and is conducted by a suction means consisting of a piping 13, a nozzle 12 and a blower 8 into the oxidizing means 3. The silicon is converted to an oxide by a combustion column in the means 3 and fed to the wet process dust collector 4 which shifts the oxide to an aq. phase. The aq. phase is then removed by a cyclone 6 and the vapor phase is released by the blower 8 via a bag filter 7.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an apparatus for producing silicon by introducing a raw material gas containing silicon into a reaction chamber and decomposing the raw material gas, and particularly relates to an apparatus for producing silicon by introducing a raw material gas containing silicon into a reaction chamber and decomposing the raw material gas. This invention relates to a device that can collect and process fine powdered silicon.

[Technical background of the invention and its problems] When a raw material gas containing silicon is introduced into a reaction chamber and this raw material gas is decomposed by glow discharge, heat, and light to produce silicon, a small amount of by-product is produced. Powdered silicon is generated in the reaction chamber and gas exhaust system.

7 morphs produced by glow discharge decomposition of higher-order silanes such as silane and disilane, and 3i halides such as SiF4? Production of silicon and microcrystalline silicon, 5iH2C
In the production of epitaxial silicon and polycrystalline silicon by thermal decomposition of 3i chlorides such as J2, and in the production of amorphous silicon and crystalline silicon by photolysis of silane and higher-order silane by irradiation with a mercury lamp, each raw material gas is decomposed. reactive active species such as ions and radicals are generated.

These reactive active species are adsorbed onto the substrate surface and silicon is deposited on the substrate. On the other hand, some of the reactive active species react in the gas phase to generate fine silicon powder.

When exhausting the unreacted raw material gas containing Si, this fine powder silicon mixes with the oil in the ribbon attached to the inside of the exhaust system, causing a significant reduction in exhaust performance. Therefore, in order to prevent this phenomenon, a dust trap equipped with a wire mesh is installed between the vacuum reaction vessel and the exhaust device, and by capturing the fine silicon powder, it is possible to prevent the fine powder silicon from entering the exhaust device. .

A method of cleaning a wire mesh with alcohol as a method for removing fine powder silicon trapped in a dust trap from the wire mesh;
The commonly used methods include suctioning with a blower or dust collector, and blowing away with high-pressure gas, but they have serious drawbacks in practice.

That is, the method of wiping with alcohol has problems such as having an adverse effect on the health of the staff due to the volatility of alcohol and requiring a long work time.

In addition, when absorbing and recovering using a dust collector or the like, there was a risk that the fine silicon powder accumulated in the pipes or in the filter could cause a dust explosion. Further, when blowing with high-pressure gas, there is a problem in that high-capacity duct equipment is required to prevent the blown-off fine silicon powder from contaminating the environment, which is expensive.

[Object of the Invention] The present invention was made in view of the above circumstances, and its purpose is to efficiently recover fine silicon powder produced in a reaction chamber during silicon production in a short time without polluting the environment. The object of the present invention is to provide a silicon fI device that can be processed safely.

[Summary of the Invention] The outline of the present invention for achieving the above-mentioned object is to guide the fine powder silicon formed in the reaction chamber and captured by the dust trap to the oxidation means by the suction means, and after the oxidation treatment to pass it through the wet dust collector. It is characterized by being configured to perform exhaust treatment.

[Embodiments of the invention] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an overall explanatory diagram of an apparatus according to an embodiment of the present invention, and FIG. 2 is a detailed sectional view of a reaction chamber.

The reference numeral 1 in FIG. 1 is a reaction device that introduces a raw material gas containing Si, decomposes it, and deposits silicon on a substrate. This reactor 11 decomposes the raw material gas by glow discharge decomposition, thermal decomposition, photodecomposition, etc. An exhaust system N2 is provided to exhaust unreacted raw material gas, gaseous by-products, and carrier gas remaining in the reaction chamber 1. Further, a dust trap 10 is disposed in the middle of the exhaust path from the reaction chamber 1 to the exhaust system w12 to trap fine powder silicon produced as a by-product in the reaction chamber 1.

First, the reaction chamber 1 and exhaust device 2 will be explained with reference to FIG. 2. The product shown in Figure 2 is for producing amorphous silicon hydroxide (hereinafter simply referred to as a-8i:H), for example, a-8i:H for electrophotographic photoreceptors.
This is a film forming apparatus.

In the figure, reference numeral 31 denotes a base, and on the upper surface of this base 31, a vacuum reaction vessel 32 forming the reaction chamber 1 is installed. Furthermore, a cylindrical counter-electrode gas ejection pipe 33 is provided inside the vacuum reaction vessel 32 .

Further, a turntable 37 is provided on the base 31 and rotates at a predetermined speed via a gear mechanism 36 using a motor 34 as a driving source. and this heater 39
A conductive drum-shaped substrate 40 such as A1 as a film-forming object is placed so as to be fitted onto the substrate.

Further, a discharge generating power source 41 such as a high frequency power source is connected to the gas ejection tube 33 which also serves as a counter electrode.

Further, the gas passage 33 of the gas ejection pipe 33 that also serves as the counter electrode
A gas introduction pipe 43 with a biased pulp 42 is connected to a portion facing the lower end side of a. Furthermore, the vacuum reaction vessel 32
Inside are exhaust holes 37a, 37 bored in the turntable 37.
b and a diffusion pump via a gas exhaust port 31a bored in the base 31.

A high vacuum exhaust system (not shown) equipped with a rotary pump, etc. is connected, and a mechanical booster pump 2A is connected.
A large flow rate exhaust system 44 equipped with an exhaust bag M2 such as a one-rotation pump 2B is connected.

Further, in the exhaust line 45 of the large-flow exhaust system 44 and on the upstream side of the exhaust device 2, the dust trap 10 for trapping active species is provided, which is provided with a wire mesh 10A. Also,
A pallet valve 11 is provided between the dust trap 10 and the exhaust bag 'a2.

Next, a configuration for treating exhaust gas exhausted from the reaction chamber 1 will be explained based on FIG. 1. If the above exhaust gas is released directly into the atmosphere, the silicon-containing raw material gas and gaseous by-products (Si2He, St3 He, H2, etc.) have the property of being easily oxidized, so they may catch fire or explode at the outlet to the atmosphere. There is a danger. In addition, 82 H in the raw material gas
a, PH3.

When doping gases such as As H3 are contained, the lethal dose of these gases is several hundred DI, so they cannot be released into the atmosphere. Therefore, in order to render the exhaust gas introduced through the exhaust bag M2 harmless, an oxidizing means such as a combustion tower 3 is provided to oxidize the exhaust gas. This combustion tower 3
A combustion gas such as propane gas or city gas is introduced through the pulp 14. The exhaust gas is stably and safely changed into silicon oxide (SiO2, etc.), water, boron oxide, phosphorus oxide, and arsenic oxide through an oxidation reaction in the combustion tower 3. This oxide is then transferred to the aqueous phase (i.e. dissolved or dispersed in water)
A wet dust collector (also called a scrubber) 4 is provided. In this wet type dust collector 4, silicon oxide that is insoluble in water is dispersed in water, and boron oxides, phosphorus oxides, etc. are dispersed in boric acid,
It becomes phosphoric acid and dissolves in water. Note that a pulp 5 is provided between the exhaust bag W12 and the combustion tower 3. Further, a cyclone 6, which is a dust collector using centrifugal force, is connected to the wet dust collector 114, and the water phase is separated and drained. The pH of this wastewater is adjusted as necessary, and the wastewater is led to wastewater treatment equipment. On the other hand, particulate components remaining in the gas phase from the wet dust collector 4 are captured by a bag filter 7, which is a dust collector using a filter cloth, and the exhaust gas is completely rendered harmless and released into the atmosphere via a blower 8.

Next, a first configuration for processing the fine powder silicon that is produced in the reaction chamber 1 and captured in the dust trap 10 is installed.
This will be explained based on FIGS.

A pulp 12 is provided in the suction port 10B of the dust trap 10.
One end of a piping 13 provided with this is connected, and the other end of this piping 13 is connected to the combustion tower 3.

This piping 13 is in a state where suction is possible via the proar 8 when the pulp 11 is closed and the pulp 12 is opened. That is, the fine powder silicon captured by the wire mesh 10A of the dust trap 10 is introduced into the combustion tower 3 via the pipe 13, and is oxidized within the combustion tower 3. The piping 13, the nozzle 12, and the blower 8 are examples of suction means that sucks the fine silicon powder captured by the dust trap 10 and guides it to the oxidizing means 3.

Next, the operation of the above embodiment will be explained.

Film Formation> First, the film forming action of a-3i; l-1 in the reaction chamber 1 will be explained. The inside of the vacuum reaction vessel 32 is set in advance to a vacuum of about 10''6 torr using a high vacuum evacuation system (not shown) such as a diffusion pump or a rotary pump (not shown).

At this time, the drum-shaped base 40 is heated by the heater 39 to
A predetermined temperature between ~300°C, preferably 240-280°C
Raise the temperature to ℃.

Further, for the purpose of uniform film formation and uniform temperature in the circumferential direction, the conductive drum-shaped substrate 40 is rotated at a predetermined circumferential speed.

Next, the gas pulp 42 is opened and S i Ha or 82
Ha, PHa, H2,02, NHs, N2, C
A gas such as Ha, C2Hs, etc. is introduced into the gas passage 33a of the gas jet tube 33 which also serves as a counter electrode in the vacuum reaction vessel 32. At the same time, valves (not shown) are switched to create a diffusion pump (not shown) with an exhaust system.

The high-vacuum exhaust system (not shown) equipped with a rotary pump and the like is switched to a high-flow exhaust system 44 equipped with an exhaust bag W12 such as a mechanical booster pump 2A and a rotary pump 2B.

Next, the gas containing silicon or other doping gas is adjusted to a predetermined flow rate in eight ways by a flow controller (not shown), and the mechanical booster pump 2A
By opening and opening a valve (not shown) connected to
The pressure within the vacuum reaction vessel 32 is set to a predetermined value between 0.1 and i torr.

On the other hand, the gas introduced into the gas passage 33a of the gas jet pipe 33 that also serves as a counter electrode is directed toward the drum-shaped base body 40 from the gas jet port 33b formed on the inner peripheral surface side of the gas jet g33 that also serves as a counter electrode. It is squirted.

After this, high frequency power with a frequency of 13.56 MHz is applied from the discharge generation power source 41 such as a high frequency power source to 20 W to IK.
A predetermined value between W is applied to the gas ejection tube 33 that also serves as a counter electrode, and a glow discharge is generated between the drum-shaped base 40 and the gas ejection tube 33 that also serves as a counter electrode.

The gas ejection tube 33 which also serves as a counter electrode is electrically insulated by an insulating ring 49, and is connected to a conductive drum-shaped substrate 40 and a reaction chamber! 32 mag is grounded.

Thus, a plasma of a gas containing silicon or a gas mixture with a gas containing silicon is generated, and amorphous silicon (a-8iH) starts to be deposited on the drum-shaped substrate 40.

Note that the silicon-containing gas that did not contribute to film formation at this time or the radicals of other gases are removed by a high-flow exhaust system 4 equipped with a mechanical booster pump 2A and a rotary pump 2B.
Exhausted via 4.

Exhaust Gas Treatment> Next, the treatment of exhaust gas discharged through the large-flow exhaust system 44 will be described. When treating exhaust gas, valve 5,
11 is opened and valve 12 is opened.

First, the exhaust gas is oxidized in the combustion tower 3, and the oxides are transferred to the water phase in the wet collection 11el14. As a result, silicon oxide that is insoluble in water is dispersed in water, and boron oxides, phosphorus oxides, etc. become boric acid, phosphoric acid, etc. and dissolve in water. The aqueous phase is then separated by a cyclone 6 and treated as wastewater, while the particles remaining in the gas phase are captured by a bag filter 7, and the exhaust gas is completely rendered harmless and released into the atmosphere via a blower 8. .

<Removal treatment of fine powder silicon> When the above-mentioned a-8i:H film was formed, reactive active species (SiHs) generated by glow discharge decomposition of 3iHa
, 5iHz, 5il-1, Si, H, etc. radicals,
The reaction of ion) III in the gas phase is unavoidable, and the vacuum reaction vessel 32 contains finely powdered silicon (for example, S in H
2n or polysilane having a 2 structure) is generated.

Since these fine silicon powders cause a pressure drop when entering the exhaust system, they are captured and collected by the dust trap 10. That is, the fine silicon powder slides down the tapered portion 50 at the bottom of the reaction vessel 32 and flows down the wire mesh 10 in the dust trap 10.
Captured by A.

After the deposition of a-3i;)l on the drum-shaped substrate 40 is completed, the valve 42 is closed to stop the supply of raw material gas.

Thereafter, after the pressure in the vacuum reaction vessel 33 is reduced to about 10-3 torr, the gas introduction pipe 43 is connected to a nitrogen gas supply device, the valve 42 is opened, and nitrogen gas is introduced into the vacuum reaction vessel 32.

Then, the exhaust device t2 is stopped on the sliding door where the raw material gas remaining in the vacuum reaction vessel 32 has been replaced with nitrogen gas. Continuing with supplying nitrogen gas into the vacuum container 32, after the pressure inside the vacuum container 32 reaches 1 atmosphere, the lid (not shown) is removed and the drum-shaped substrate 40 on which a-3i; l-1 has been deposited is taken out.

Next, turn valve 5.11 from open to leap, and reverse valve 12.
from closed to open, the fine silicon powder captured and collected in the dust trap 10 is sucked from the suction port 10B, and the pipe 13
is introduced into the combustion tower 3 through. At this time, the valve 14 is opened and city gas is supplied.

Combustion gas such as propane gas is simultaneously introduced into the combustion tower 3 and ignited to oxidize (combust) the fine silicon powder. The silicon oxide is sent to a scrubber 4.

Here, more than 95% of silicon oxide is dispersed in water,
It is drained through cyclone 6 and treated.

The remaining several percent of silicon oxide that did not move to the aqueous phase is captured by the bag filter 7. Note that only 0.1% or less of silicon is released into the atmosphere.

As described above, in the apparatus of this embodiment, the finely powdered silicon that is by-produced in the reaction chamber 1 and captured in the dust trap 10 is sucked into the combustion tower 3, and the oxidized silicon oxide is passed through the wet dust collector 4. Since the wastewater is treated as waste water or released into the atmosphere, silicon can be produced while preventing environmental pollution.

Moreover, since the above-mentioned processing can be performed without taking out the wire mesh 10A in the dust trap 10, the fine powder silicon can be efficiently removed in a short time and processed safely. The capacity of the dust trap 10 can be kept to a minimum by processing the fine silicon powder captured in the dust trap 10 for each batch.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention. For example, the oxidation means is not limited to a combustion tower, but may also utilize a catalyst. Further, the suction source for the fine powder silicon is not limited to the blower provided after the exhaust gas treatment, but may be provided exclusively.

[Effects of the Invention] The silicon manufacturing apparatus of the present invention described in detail above can safely and safely collect fine powder silicon, which is produced in a reaction chamber during silicon manufacturing and is captured in a dust trap, with a relatively simple configuration. It can be efficiently and reliably removed without causing environmental pollution.

[Brief explanation of drawings]

FIG. 1 is an overall explanatory diagram showing one embodiment of the present invention, and FIG. 2 is a detailed sectional view of a reaction chamber. 1... Reaction chamber, 3... Oxidation means, 4... Wet type dust collector, 10... Dust trap, 8.12.13... Suction means.

Claims (2)

[Claims] (1) A reaction chamber in which a raw material gas containing silicon is introduced, decomposed and reacted to deposit silicon on a substrate, and unreacted raw material gas and gaseous by-products remaining in this reaction chamber are introduced. an oxidizing means for oxidizing oxides, a wet dust collector for transferring oxides oxidized by the oxidizing means to an aqueous phase, and a wet dust collector disposed in the exhaust route between the reaction chamber and the oxidizing means to remove by-products from the oxides produced in the reaction chamber. 1. A silicon manufacturing apparatus comprising: a dust trap that captures the finely powdered silicon; and a suction means that sucks the finely powdered silicon captured by the dust trap and guides it to the oxidizing means. (2) The silicon manufacturing apparatus according to claim 1, wherein the silicon deposited on the substrate is amorphous silicon.