WO2015008889A1 - Device and method for manufacturing polysilicon - Google Patents

Abstract

The present invention relates to a thermal plasma fluidized bed reaction device, and the purpose of the present invention is to provide a thermal plasma fluidized bed reaction device capable of producing high-purity polysilicon continuously while consuming less power, thereby reducing manufacturing costs. In order to accomplish the purpose, the present invention provides a thermal plasma fluidized bed reaction device for manufacturing silicon, the device comprising: a plasma fluidized bed reactor; a plasma granulator; and a connector for connecting the plasma fluidized bed reactor and the plasma granulator. Furthermore, the present invention provides the most economic and efficient method for manufacturing polysilicon by recycling and using the entire byproduct generated when polysilicon is manufactured.

Description

Polysilicon Manufacturing Apparatus and Method

The invention of the first material of the polysilicon decompose the hydrofluoric acid sodium (Na ₂ SiF ₆₎ and SiF decomposition step of generating ₄ (Decomposition Process), the above generated SiF ₄ for using the hydrogen reduction in the thermal plasma fluid bed reactor Economically and efficiently high-purity polysilicon through a closed process for producing Na ₂ SiF ₆ by recycling the Reduction process, reactant SiO ₂ and by-products NaF and HF generated in the above decomposition and reduction steps The present invention relates to a device for producing polysilicon, and a method for producing polysilicon and polysilicon according to the present invention relates to a thermal plasma fluidized bed reactor, and more particularly, to continuously produce while reducing power consumption, thereby reducing manufacturing cost and producing high purity poly. Fluidized bed reactor and plasma granulator composed of reactant feeder, reaction part to produce silicon The present invention relates to a thermal plasma fluidized bed reactor comprising a connection pipe connecting a reactor and a plasma granulator.

Polysilicon, which can be used as a main raw material in the semiconductor or photovoltaic industry, is usually made of metallurgical-grade silicon (MG-Si) by reducing the oxygen of raw materials by reducing the quartz or sand with carbon. Metal-grade silicon is further refined to make high-purity solar cell or semiconductor silicon.

Siemens method, Fluidized Bed Reactor method, VLD (Vapor-to-Liquid Deposition) method, or metallurgy direct refining method are mainly used for the purification of metal grade polysilicon.

The most commonly used method is the Siemens method developed in the 1950s and widely used to date. This method involves reacting metallic silicon with HCl to react trichlorosilane gas represented by SiHCl ₃ or metallic silicon with SiCl ₄ and H ₂ or reacting with SiF ₄ and NaAlH ₄ to produce monosilane gas represented by SiH ₄ . After obtaining, the raw material mixed with the gas and hydrogen is injected into a ∩-shaped silicon core rod (Rod) heated to about 1100 ° C. to deposit silicon on the ∩-shaped silicon core rod through a pyrolysis reaction. However, this method has a problem in that the electricity consumption is high, the equipment investment cost is high, and the productivity is low because it is required to maintain a high temperature of 1000 ℃ or more by applying strong electricity to the silicon core rod.

In addition, in the fluidized bed method, silicon seed particles are introduced into a crucible through which hydrogen gas flows, and silane gas such as chloride silane or trichloride is injected, so that the injected silicon seed particles fall, and granular silicon having a diameter of about 1 cm is used. It is a way to precipitate out. Although the silicon precipitation rate is about 100 times faster than the Siemens method, there is a problem that the quality is somewhat lower.

Japanese Laid-Open Patent Publication No. 2008-143756 discloses a method and apparatus for manufacturing high purity silicon using arc plasma, fluorine-based silicon gas and silane gas.

In addition, Japanese Laid-Open Patent Publication No. 2004-525841 discloses a plasma region generated by applying electric power in a hydrogen atmosphere containing silicon fluoride gas or silane gas as a reaction gas, and decomposing the reaction gas into plasma, and at the same time silicon seed (seed). Disclosed is a technique for freely dropping particles in the plasma region to deposit silicon separated from the reaction gas on the surface of silicon seed particles.

 U.S. Patent No. 6926876 discloses a method for producing polysilicon metal from a halogenated silicon plasma source, wherein the halogenated silicon is spliced into silicon and halogen ions in an inductively coupled plasma, and the silicon ions are condensed. To disclose molten silicon, and halogen ions react with silica sand for reuse.

Meanwhile, Korean Laid-Open Patent Publication No. 2010-0042372 discloses a thermal plasma fluidized bed reactor for producing silicon, including a plasma torch unit, a reactant, a gas supply unit, and a fluidized bed reactor, and a method for producing silicon using the reactor.

However, the known plasma fluidized bed reaction apparatus has been pointed out that the process is complicated and expensive by separately installing the granulator device, and the problem of separately processing the dispersion.

Accordingly, the present inventors have made efforts to solve the above problems, and as a result, the surplus by-products can be reused through the closing process, and the silicon fluid includes a plasma fluidized bed reactor and a plasma granulator, and a connection portion connecting the plasma fluidized bed reactor and the plasma granulator. When silicon is produced using a thermal plasma fluidized bed reactor for manufacturing, the thermal efficiency is high, and when a plasma reactor is used, the product can be directly produced without a separate granulator capable of granulating fine products. Although it was not possible to recover the fine powder discharged to the top, the present invention confirmed the advantage that can be collected by collecting the fine powder and granulated through a plasma reactor, to complete the present invention.

Summary of the Invention

The present invention relates to a thermal plasma fluidized bed reactor, and an object of the present invention is to provide a thermal plasma fluidized bed reactor capable of producing high-purity polysilicon by reducing the production cost by continuously producing power consumption.

In order to achieve the above object, the present invention provides a thermal plasma fluidized bed reaction apparatus for manufacturing a silicon fluid comprising a plasma fluidized bed reactor and a plasma granulator and a connection portion connecting the plasma fluidized bed reactor and the plasma granulator.

Furthermore, the present invention provides the most economical and efficient method of producing polysilicon by recycling the entire by-product in the production of polysilicon.

1 is a view showing a step-by-step polysilicon manufacturing process according to the present invention.

2 is a view showing a plasma fluidized bed reactor according to the present invention.

Detailed Description of the Invention and Specific Embodiments

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

The present invention is Na ₂ SiF ₆ decomposition step, SiF ₄ reduction step, a high purity of the recycle step for producing the Na ₂ SiF ₆ and the NaF and HF by-product generated in the decomposition step and the reduction step as a raw material through the closing process (Closed Process) Provided are methods of making polysilicon.

In another aspect, the present invention is a thermal plasma fluidized bed reactor for producing silicon, comprising a plasma fluidized bed reactor, a plasma granulation chamber, first to third chambers functioning as a plasma granulator, and a plasma granulation chamber for granulating silicon fine powder generated in the plasma fluidized bed reactor. To provide.

The present invention provides a plasma fluidized bed reactor for reducing the reaction gas, which is a raw material for producing silicon, to H ₂ gas, which is a reducing agent, by the first electrode for generating a high temperature thermal plasma. A first chamber, a second chamber, a connection portion between the first chamber and the second chamber, and a third chamber for recovering and granulating the silicon fine powder generated in the plasma fluidized bed reactor; The present invention relates to a polysilicon manufacturing apparatus including a second electrode portion for granulating the rate-controlled silicon fine powder passing through the third chamber, a plasma granulation chamber including the second electrode portion, and a granulated silicon product second outlet.

In another aspect, the present invention comprises the steps of (a) decomposing the reactant Na ₂ SiF ₆ to generate NaF as a product of SiF ₄ and by-products; (b) hydrogen reducing reactant SiF ₄ to produce HF from the product silicon and by-products; (c) a method for producing polysilicon, comprising reacting SiO ₂ and byproduct NaF and HF generated in steps (a) and (b) to produce Na ₂ SiF ₆ and reusing in step (a) .

In the present invention, the reaction scheme of each step of the silicon manufacturing method is as follows.

(a) Na ₂ SiF ₆ → SiF ₄ + 2 NaF

(b) SiF ₄ + H ₂ → Si + 4HF

(c) SiO ₂ + 2NaF + 4HF → Na ₂ SiF ₆ + 2H ₂ O

Figure 1 shows the entire silicon manufacturing process of the present invention.

Step 1 shows a decompositiomn process of Na ₂ SiF ₆ which is a raw material of polysilicon. The first required Na ₂ SiF ₆ used in the present invention uses sodium silicate fluoride (Na ₂ SiF ₆ ) precipitated from an aqueous solution of silicon fluoride produced when the phosphate rock is converted into fertilizer. Na ₂ SiF ₆ of the present invention by the thermal decomposition is simply decomposed into silicon tetrafluoride (SiF ₄₎ and sodium fluoride (NaF). Here, silicon tetrafluoride, a decomposition product, is used in the production of pure silicon after being introduced into a step 2 reduction process, and another decomposition product, sodium fluoride (NaF), is circulated in a step 3 recycling step to produce Na ₂ SiF, a raw material of polysilicon. ₆ is used for the preparation.

Reduction process of step 2 is prepared by using hydrogen tetrafluoride (SiF ₄ ) produced in the decomposition step 1 as a raw material only hydrogen to produce pure polysilicon using the thermal plasma fluidized bed reactor of the present invention described above It is. The greatest feature of the thermal plasma fluidized bed reactor of the present invention is that it is possible to manufacture pure polysilicon while improving efficiency and economic efficiency by integrally connecting the thermal plasma fluidized bed reactor and the granulator device without installing a separate granulator device. will be. Hydrogen fluoride (HF) produced in the step 2 reduction step is recycled to the step 3 recycle step and used to prepare Na ₂ SiF ₆ , which is a raw material of polysilicon, with sodium fluoride (NaF) circulated in the step 1 decomposition step.

The recycling process of step 3 is to prepare Na ₂ SiF ₆ using SiO ₂ and sodium fluoride (NaF) and hydrogen fluoride (HF) circulated in steps 1 and 2 as raw materials. In the step 3 recycling step of the present invention, diatomaceous earth is used as SiO ₂ as a raw material.

As described above, the polysilicon manufacturing process of the present invention uses the first and third stages of the closed process, and the first required Na ₂ SiF ₆ precipitated from an aqueous solution of silicon fluoride generated when the phosphate rock is converted into fertilizer. Apart from adding hydrogen and diatomaceous earth (SiO ₂ ), which are intermediate supplementary raw materials, pure polysilicon can be produced most economically and efficiently by recycling the by-products generated in the process.

In the present invention, the plasma fluidized bed reactor includes a first electrode part 100, a plasma fluidized bed reactor 110, a polysilicon product outlet 10, a first chamber 120, a reactant and a reactant gas supply (1). The first electrode unit 100 is a plasma fluidized bed reactor in the present invention is to generate a plasma, and includes all types of electrodes for generating a plasma that can supply heat to the plasma fluidized bed reactor For example, a hollow type electrode is used, and is inserted and coupled downward, for example, and a power line receiving power from a power supply unit is connected to a lower end, and plasma power is supplied from the power supply unit to cause arc discharge. It may be to generate a high temperature thermal plasma inside the plasma fluidized bed reactor.

As such, when the thermal reduction reaction between the reactant and the reaction gas is performed by using a high temperature heat plasma, and even when a low-cost raw material is used, the thermal reduction reaction can be accelerated, so that silicon particles of high purity can be continuously produced more easily.

That is, the thermal plasma generates molecules and atoms having a high energy in the first chamber, and thus the reactants and the reactant gas supplied to the first chamber internal space use high temperature thermal energy generated by the thermal plasma. Since it causes a heat reduction reaction, the activation energy is reduced and the chemical reaction is accelerated, so that the heat reduction reaction can be more easily caused.

On the other hand, the first electrode portion can be detachable for easy management, and connecting members such as O-rings may be used to minimize the occurrence of gaps in the connecting portion, but is not limited thereto.

In addition, the inner wall of the plasma fluidized bed reactor is made of steel, and the steel is made of high-temperature alloys (Incoly, Inconel, hastellay), and a silicon carbide coated cylindrical liner is inserted to prevent impurities.

In addition, it is preferable to use a ceramic insulator for external insulation on the outer peripheral surface of the first electrode portion.

As described above, when a thermal plasma is generated from the first electrode unit 100 after the reactant and the reaction gas are supplied to the plasma fluidized bed reactor 110, the internal space of the plasma fluidized bed reactor 110 is heated, and As the silicon particles start to move, they form a fluidized bed and the reaction gas (SiF ₄ ) causes a thermal reduction reaction. The reaction gas causing the heat reduction reaction continuously causes the heat reduction reaction while circulating inside the plasma fluidized bed reactor by the carrier gas, thereby depositing silicon on the surface of the flowing high temperature silicon powder particles, and the size of the silicon particles. Is gradually increased to grow to a constant size, it is possible to obtain a high-purity silicon particles by collecting and recovering. That is, within the plasma fluidized bed reactor 110, a reduction reaction by plasma and a reduction reaction by high temperature occur in the fluidized bed, and the polysilicon product having an average particle diameter of 1000 μm (1 mm) is recovered through the polysilicon product outlet 10. do.

In the present invention, the reaction gas supply unit 1 is for supplying a reactant to the plasma fluidized bed reactor (110).

The reaction gas is silicon crystal powder, trichlorosilane, silane (Monosilane), silicon tetrafluoride, silicon tetrachloride, etc., it is preferable to use hydrogen as a reducing agent.

The plasma fluidized bed reactor of the present invention is characterized in that the first chamber 120 for granulating the fine powder produced in the plasma fluidized bed reactor into silicon crystal powder. The first chamber 120 recovers the silicon particles generated in the plasma fluidized bed reactor 110 and then collects the unrecovered fine particles. In other words, it is characterized by trapping the fine powder of silicon fine powder by reducing the speed to fly less by the principle of expansion (Expansion).

The silicon fine powder and the unreacted reactant gas collected in the first chamber 120 enter the second chamber 140 through the connection unit 130.

In the second chamber 140, an unreacted reaction gas discharge unit 11 for recovering unreacted reaction gas is installed.

The pure silicon fine powder passing through the second chamber 140 is collected while adjusting the speed in the third chamber 150.

The silicon fine powder controlled by the speed while passing through the third chamber 150 passes through the second electrode unit 160 and is subjected to granulation with an average particle diameter of 1000 μm (1 mm) as silicon particles.

The second electrode part of the present invention uses the same plasma reactor as the first electrode part, and is installed inside the plasma granulation chamber 170.

The silicon product granulated in the plasma granulation chamber 170 with an average particle diameter of 1000 μm (1 mm) is recovered through the second silicon product outlet 12.

As described above, the present invention can recover the total amount of the silicon fine powder that is not deposited in the plasma fluidized bed reactor through the first chamber and the second chamber having the form of diffusion, so that a separate granule device is not provided as in the prior art. It is characterized by providing a silicon recovery apparatus.

That is, in the existing fluidized bed reactor, the fine powder discharged to the upper part cannot be recovered, but the present invention has the advantage of collecting the fine powder to be recovered by granulation through a plasma reactor.

Carrier gas may be further used in the present invention, the carrier gas is characterized in that selected from the group consisting of argon, nitrogen and helium.

2 is a view showing a plasma fluidized bed reactor of the present invention.

The thermal plasma fluidized bed reactor of the present invention includes a plasma fluidized bed reactor 110, a first electrode part 100, a first chamber 120, and a reactant supply part 1, and a second chamber 140 and a third chamber. And a second electrode part 160 and a granulation chamber 170, wherein the connection part 130 connects the upper end of the plasma fluidized bed first chamber 120 to the second chamber 140. ).

As described above in detail the specific parts of the present invention, it is apparent to those skilled in the art that such specific description is merely a preferred embodiment, thereby not limiting the scope of the present invention. something to do. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

The thermal plasma fluidized bed reactor according to the present invention has a high thermal efficiency by using a fluidized bed reactor, and when the plasma reactor is used, it is possible to directly produce a product without a separate granulator capable of granulating fine products.

In addition, the conventional fluidized bed reactor can not recover the fine powder discharged to the top, but the present invention has the advantage that can be collected by collecting the fine particles to be granulated through a plasma reactor.

Furthermore, the present invention provides the most economical and efficient method of producing polysilicon by recycling the entire by-product in the production of polysilicon.

Claims (5)

Polysilicon manufacturing apparatus comprising the following components: A plasma fluidized bed reactor for reducing the reaction gas, which is a raw material for producing silicon, to H ₂ gas, which is a reducing agent, by the first electrode for generating a high temperature thermal plasma and granulating the reaction gas; A first chamber, a second chamber, a connection portion between the first chamber and the second chamber, and a third chamber for recovering and granulating the silicon fine powder generated in the plasma fluidized bed reactor; A second electrode portion for granulating the rate-controlled silicon fine powder that has passed through the third chamber, a plasma granulation chamber comprising the second electrode portion, and a granulated silicon product second outlet. The method of claim 1, wherein the reaction gas is selected from the group consisting of trichlorosilane (trichlorosilane), silane (Monosilane), silicon tetrafluoride (silicon tetrafluoride), silicon tetrachloride (polysilicon), characterized in that the production of polysilicon Device. Polysilicon manufacturing method comprising the following steps: (a) decomposing the reactant Na ₂ SiF ₆ to generate NaF as a product SiF ₄ and by-products; (b) hydrogen reducing reactant SiF ₄ to produce HF from the product silicon and by-products; (c) recycling the reactants SiO ₂ and by-products NaF and HF generated in steps (a) and (b) to produce Na ₂ SiF ₆ and reusing in step (a). 4. The method of claim 3, wherein the reactant SiO ₂ of step (c) is diatomaceous earth. 4. The method of claim 3, wherein step (b) uses a thermal plasma fluidized bed reactor equipped with the following components: A plasma fluidized bed reactor for reducing the reaction gas, which is a raw material for producing silicon, to H ₂ gas, which is a reducing agent, by the first electrode for generating a high temperature thermal plasma and granulating the reaction gas; A first chamber, a second chamber, a connection portion between the first chamber and the second chamber, and a third chamber for recovering and granulating the silicon fine powder generated in the plasma fluidized bed reactor; A second electrode portion for granulating the rate-controlled silicon fine powder that has passed through the third chamber, a plasma granulation chamber comprising the second electrode portion, and a granulated silicon product second outlet.

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