KR20160144541A

KR20160144541A - Method for producing trichlorosilane

Info

Publication number: KR20160144541A
Application number: KR1020150080611A
Authority: KR
Inventors: 김흥성; 강경훈; 박수환; 전문규; 박종현
Original assignee: 주식회사 케이씨씨
Priority date: 2015-06-08
Filing date: 2015-06-08
Publication date: 2016-12-19

Abstract

The present invention relates to a method for producing trichlorosilane, comprising the steps of: preparing a trichlorosilane by supplying silicon tetrachloride and hydrogen to a reactor including a metallic silicon reaction layer and a catalyst; A step of supplying chlorine, hydrogen chloride, or a mixture thereof to a region at or above the height of the reactor and adjusting the reaction conditions at the upper portion of the reactor reaction layer to simultaneously produce the trichlorosilane to improve the conversion efficiency of the trichlorosilane, And to a method for producing trichlorosilane capable of improving the efficiency.

Description

[0001] The present invention relates to a method for producing trichlorosilane,

The present invention relates to a process for preparing trichlorosilane.

High purity trichlorosilane (TCS) is used as a raw material for the production of polycrystalline silicon used in the photovoltaic industry, or in the semiconductor industry. As a method for producing polycrystalline silicon for solar cells using trichlorosilane, a method of reducing silicon trichloride gas to hydrogen gas or pyrolyzing silicon to precipitate silicon is mainly used. For the silicon deposition method, a Bell jar reactor or a fluidized bed reactor (FBR) is typically used. In the method using a bell-shaped reactor, silicon trichloride and hydrogen gas are placed in a vertical reactor and the silicon rod is heated to a high temperature by using electricity to deposit silicon. In a method using a fluidized bed reactor, silicon particles having a small size are injected into a reactor and heated while being fluidized, and silicon seed particles are continuously supplied to the reactor, whereby silicon is precipitated from the surface of the silicon seed particles, This is a method for obtaining a polycrystalline silicon having a large size.

In both of the above methods, hydrogen chloride and silicon tetrachloride, which are byproducts, are generated and discharged together with unreacted trichlorosilane, and the discharged trichlorosilane is separated and used as a raw material for polycrystalline silicon production again. At this time, the production efficiency of silicon can be increased by producing trichlorosilane, which is a raw material for producing polycrystalline silicon, using byproducts such as silicon tetrachloride and hydrogen chloride, and as a result, polycrystalline silicon can be economically produced and thus a competitive power can be obtained.

Generally, as a method for increasing the conversion rate of trichlorosilane, hydrochlorination is used to produce trichlorosilane by reaction with metallic silicon and hydrogen in the case of silicon tetrachloride. In the case of hydrogen chloride, trichlorosilane And chlorination (chlorination) to produce silane. The hydrochlorination reaction is an endothermic reaction, and generally exhibits an optimum trichlorosilane conversion at a temperature of 530 to 580 ° C and 28 to 33 barg. The chlorination reaction is an exothermic reaction and is generally carried out at a temperature of 300 to 340 ° C. and 1 to 3 barg Lt; / RTI > Each reaction formula is as follows.

* Hydrochlorination reaction: Si + 2 H ₂ + 3 SiCl ₄ ← → 4 HSiCl ₃

* Chlorination: 3 HCl + Si ← → HSiCl ₃ + H ₂

Since the two reactions require different reactors and manufacturing processes due to different reaction conditions, the production process of trichlorosilane is complicated and the investment cost is high, which is inefficient. Therefore, a method of simultaneously introducing hydrogen chloride into the hydrochlorination reaction has been studied.

For example, Japanese Patent Application Laid-Open No. 1983-161915 discloses a method of simultaneously introducing hydrogen chloride into the lower part of the reaction layer in the reaction of silicon tetrachloride, metallic silicon and hydrogen. However, since hydrogen chloride, which is not intended to improve the conversion of trichlorosilane, And to reduce the energy by further heating by the exothermic reaction of the heat.

U.S. Patent No. 4,526,769 discloses a two-stage reactor in which one reaction is conducted at a different reaction temperature in a first reactor in which the reaction temperature is 500 to 700 ° C. In the first reactor, silicon tetrachloride, metallic silicon, and hydrogen And the reaction product obtained is reacted with hydrogen chloride in a second reactor at 300 to 350 ° C to increase the conversion of trichlorosilane. Since this method requires a two-step reaction, there is a problem that the manufacturing process of the trichlorosilane is complicated, the investment cost is large, and it is difficult to actually apply the process.

U.S. Patent Publication No. 2004-0047793 discloses a silicon tetrachloride, a metallic silicon and a bar, which is the residence time of the hydrogen chloride the reaction layer hayeotneun discloses a method for simultaneously added a hydrogen chloride in the reaction of hydrogen and silicon tetrachloride by 10 ^- 50% in the ³ Thereby increasing the conversion of trichlorosilane. This method is advantageous in that the conversion rate of the trichlorosilane is higher than the method of introducing hydrogen chloride into the lower part of the reaction layer. However, when the hydrogen chloride introduced at the high temperature (450 to 800 ° C) is converted into the tetrachlorosilane by reaction with the generated trichlorosilane, There is a problem that it is difficult to maximize the conversion ratio of the trichlorosilane by converting the generated trichlorosilane into silicon tetrachloride, hydrogen and silicon again by the reverse reaction. The higher the temperature and the higher the concentration of trichlorosilane, the greater the possibility of reaction and reverse reaction between trichlorosilane and hydrogen chloride. Each reaction formula is as follows.

* HSiCl ₃ + HCl ← → SiCl ₄ + H ₂

* 4 HSiCl ₃ ← → Si + 2 H ₂ + 3 SiCl ₄

Korean Patent No. 10-2009-0108288 discloses a method of simultaneously introducing hydrogen chloride or chlorine into a reaction with silicon tetrachloride, metallic silicon, and hydrogen, in which hydrogen chloride or chlorine is reacted with silicon tetrachloride and hydrogen to form a metallic silicon reaction layer The hydrogen chloride introduced into the reactor at a high temperature (400 to 700 ° C) is reacted with the generated trichlorosilane to convert it into tetrachlorosilane or the generated trichlorosilane is reacted again with silicon tetrachloride, hydrogen and silicon There is a problem that it is difficult to maximize the conversion rate of trichlorosilane.

The present invention relates to a process for the production of trichlorosilane by providing silicon tetrachloride and hydrogen to a reactor comprising a metallic silicon reaction layer and a catalyst to produce a trichlorosilane in the reactor and at a point at or above the point at which the total height of the metallic silicon reaction layer is 70% It is a technical object of the present invention to provide a process for producing trichlorosilane which can improve the economical efficiency and efficiency of the process by simultaneously performing the step of supplying trichlorosilane by supplying chlorine, hydrogen chloride, or a mixture thereof, .

According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: filling a reactor with a metallic silicon reaction layer and a catalyst; A second step of producing trichlorosilane by supplying silicon tetrachloride and hydrogen to the reactor; And a third step of producing trichlorosilane by supplying chlorine, hydrogen chloride, or a mixture thereof to a region at or above a point which is 70% of the total height of the metallic silicon reaction layer in the reactor. to provide.

When the trichlorosilane is produced by the process of the present invention, the hydrochlorofluorination reaction and the chlorination reaction can be performed at the same time, thereby maximizing the conversion ratio of the trichlorosilane. Further, the by-product hydrogen chloride, So that the economical efficiency and the efficiency of the process can be improved.

FIG. 1 schematically shows a process for producing a polycrystalline silicon including a process for producing trichlorosilane of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The method for producing trichlorosilane according to the present invention comprises the steps of: filling a reactor with a metallic silicon reaction layer and a catalyst; A second step of producing trichlorosilane by supplying silicon tetrachloride and hydrogen to the reactor; And a third step of producing trichlorosilane by supplying chlorine, hydrogen chloride, or a mixture thereof to a region at or above a point where the height of the metallic silicon reaction layer is 70% of the total height of the metallic silicon reaction layer in the reactor.

The reaction of silicon tetrachloride and hydrogen with metallic silicon to convert silicon tetrachloride to trichlorosilane (second stage) is an endothermic reaction requiring 3 to 6 Kcal / mol of thermal energy. On the other hand, the reaction of hydrogen chloride with metallic silicon to produce trichlorosilane (the third step) is an exothermic reaction which proceeds with a heat energy of 50 Kcal / mol. Therefore, in the present invention, chlorination or hydrogen chloride may be added to the hydrochlorination reaction using metallic silicon, silicon tetrachloride, and hydrogen, so that the chlorination reaction can be simultaneously provided, thereby improving the efficiency of the trichlorosilane and the process efficiency.

In the first step of the trichlorosilane manufacturing method of the present invention, the metallic silicon reaction layer and the catalyst may be filled in the reactor. But not limited to, a conventional reactor such as a fluidized bed reactor or a fixed bed reactor, and may be, for example, a fluidized bed reactor.

The reaction temperature in the second step in the reactor may be 400 to 700 占 폚, for example, 450 to 670 占 폚, for example, 500 to 620 占 폚. When the reaction temperature is too low, the reactivity is low and the conversion rate of silicon tetrachloride (STC) to trichlorosilane (TCS) is low. On the contrary, if too high, much energy is consumed and many byproducts such as high boiling point compounds are produced.

Further, the reaction pressure in the reactor is performed under a pressure of 1 to 40 barg, for example, 15 to 30 barg. When the reaction pressure is too low, the reactivity is low and the conversion rate of the introduced silicon tetrachloride to the trichlorosilane becomes very low. On the contrary, when the reaction pressure is too high, a reactor made of a special material capable of withstanding high pressure is required. .

The catalyst used in the second step reaction may be any catalyst that can be used in the reaction for converting silicon tetrachloride into trichlorosilane without any particular limitation. For example, copper catalysts such as copper (Cu ) Metal, or copper halide such as copper (I) (CuCl) or copper (II) chloride (CuCl2) may be used.

The content of the catalyst is not particularly limited, but 0.1 to 5% by weight, for example 0.3 to 2% by weight, of the total amount of the reactants can be used in terms of reaction and overall process efficiency.

The metallic silicon (MG Si) used as the starting material of the second-step reaction is a silicon having a purity of about 98% or more, prepared by reacting silicon dioxide (SiO ₂ ) ores with a reducing agent such as carbon, 500 mu m, for example, 50 mu m to 450 mu m can be used. If the size of the metallic silicon particles is too small, the metallic silicon tends to escape from the reactor without participating in the reaction due to the fluidization in the reactor. Conversely, if the size is too large, effective fluidization can not be achieved. it's difficult.

As shown in FIG. 1, the metallic silicon 3 is filled in the fluidization reactor 4 in the first step, the raw material gases (silicon tetrachloride, hydrogen, etc.) are injected in the lower part of the reactor in the second step, The content of the metallic silicon is not particularly limited as long as the content of the metallic silicon is in excess of the quantitative reaction in the reactor.

In addition, hydrogen as a starting material of the second step reaction may be 1 to 10 moles, for example, 1.5 to 7 moles, for example, 2 to 5 moles, per 1 mole of silicon tetrachloride. When the amount of hydrogen is too small, the conversion rate of silicon tetrachloride to trichlorosilane becomes very low. On the contrary, when too much hydrogen is used, excess energy is required to heat an excessive amount of hydrogen and it is difficult to recover unreacted hydrogen.

The third step reaction may be performed simultaneously with the second step reaction, and the reactant chlorine, hydrogen chloride, or a mixture thereof may be carried on the metallic silicon reaction layer in the reactor, for example, above or above the fluidized reaction layer of the metallic silicon Trichlorosilane can be prepared by putting it in a region at or above 70% height, preferably 80%, more preferably 90% of the total height of the metallic silicon reaction layer, .

When chlorine, hydrogen chloride, or a mixture thereof is introduced into the lower portion of the reaction layer, hydrogen chloride reacts with metallic silicon to produce trichlorosilane, but the conversion of trichlorosilane can not be maximized under high temperature (400 to 700 ° C). In addition, the longer the residence time of the hydrogen chloride and the reaction product in the reaction layer 3 in the reactor where the high temperature is maintained and the free board 5 outside the reaction layer, the lower the conversion rate of the trichlorosilane by the reaction such as the reverse reaction As used herein, the term " free board " refers to an empty space other than the space occupied by the metallic silicon reaction layer initially filled in the reactor). The reaction of the second stage reaction, silicon tetrachloride, metallic silicon and hydrogen, is required to maintain the inside of the reaction layer at a high temperature in order to increase the conversion rate of the triflate silane by endothermic reaction. It is possible to maximize the conversion rate of trichlorosilane by reducing the temperature of the free space outside the reaction layer while minimizing the residence time by injecting chlorine, hydrogen chloride or a mixture thereof as the reactant in the third step into the upper part of the reaction layer.

In the third step of the present invention, hydrogen chloride and chlorine may be introduced into the free space outside the fluidization reaction layer, that is, the reaction product and the metallic silicon fine powder, to increase the conversion rate of the trichlorosilane by reacting with metallic silicon powder. For example, hydrogen chloride and chlorine can also be introduced into the cyclone portion 6 where the silicon fine powder contained in the reaction product discharged from the reactor is separated and re-supplied to the reactor.

Although not particularly limited, the residence time of the chlorine, hydrogen chloride or a mixture thereof as the reactant in the third step may be 0.01 to 100 seconds, for example, 0.01 to 10 seconds, for example, 0.01 to 5 seconds. If the residence time is too short or too long, the conversion of trichlorosilane may be low.

The hydrogen chloride, chlorine, or a mixture thereof in the third step may be 0.01 to 10 moles, for example, 0.01 to 7 moles, for example, 0.01 to 5 moles, per mole of silicon tetrachloride. The conversion rate of trichlorosilane increases as the molarity of the reactant increases, while the conversion rate of hydrogen chloride is too low to allow unreacted hydrogen chloride to be included in the reaction product.

In the process for producing trichlorosilane of the present invention, silicon tetrachloride, hydrogen and hydrogen chloride used as a reactant may be recovered as a by-product in the polycrystalline silicon production process, or further supplied from the outside may be used. In FIG. 1, the reaction product discharged from the reactor is separated into crude TCS and hydrogen gas by a separation process, and the separated hydrogen gas is supplied to the lower portion of the reactor and used as a reactant in the second stage, Can be used for the quenching effect in the reaction of the third step. The crude TCS in the liquid phase is a chlorosilane mixture containing trichlorosilane and silicon tetrachloride, which may be supplied to the upper portion of the reaction layer before purification to be used for the quenching effect in the third step reaction. The purified silicon tetrachloride is separated into pure trichlorosilane (TCS) and silicon tetrachloride (STC) through purification, and the separated silicon tetrachloride is supplied to the lower part of the reactor as the second-stage reaction material or supplied to the upper part of the reaction layer, Can be used for the quenching effect. Polysilicon (polycrystalline silicon) can be obtained by reducing purified trichlorosilane, and hydrogen and hydrogen chloride gas, which are off gases discharged during the reduction process, can be recovered through the off-gas recovery process. The recovered hydrogen gas may be fed to a reduction or TCS synthesis reactor and hydrogen chloride may be fed to the TCS synthesis reactor to be used as a reactant.

The trichlorosilane production method of the present invention can cool the temperature of the free space outside the reaction layer by various methods to improve the conversion of trichlorosilane, and is not particularly limited, but may be lowered to 100 to 500 ° C. Although not particularly limited, a mixture of hydrogen, silicon tetrachloride, or chlorosilane, for example, hydrogen, liquid silicon tetrachloride or chlorosilane cooled to -20 to 50 ° C may be supplied to the free space in the reactor, Can be lowered. The chlorosilane mixture may have been discharged from the separation process and the silicon tetrachloride may have been discharged from the purification process and the amount of the cooled hydrogen, liquid silicon tetrachloride or chlorosilane mixture is higher than that of the second stage silicon tetrachloride 1 And may be 0.5 to 10 moles per mole.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited to these examples.

[ Example 1 to 3]

330 g of metallic silicon having a particle size of 100-212 μm dried at 100 ° C. as a reactant and 0.5 wt% (1.65 g) of CuCl catalyst were put into a reactor of stainless steel (SUS 316) having a length of 985 mm and a diameter of 1 inch A small amount of nitrogen gas was supplied for 10 hours while heating to a temperature of 150 DEG C to remove metallic silicon and moisture in the reactor. Thereafter, nitrogen gas was converted into hydrogen gas while heating the reaction temperature to 530 DEG C, and maintained for 1 hour to induce activation of the metallic silicon surface.

The pressure of the reactor was increased to 1 bar by using hydrogen gas. Silicon tetrachloride was injected into the reactor at 0.56 g / min by using a liquid phase metering pump (HPLC). Hydrogen and hydrogen chloride were fed into the reactor using a mass flow controller [Table 1] < tb > < TABLE > Silicon tetrachloride and hydrogen were heated and vaporized to 200 ° C through a preheater before the reactor was charged, and hydrogen chloride was introduced into the gas phase without any additional heating. The reaction temperature was maintained by installing an electric heating device (jacket type) outside the reactor. The amount of hydrogen chloride was changed by changing the input amount and the input position as shown in [Table 1]. When hydrogen chloride was introduced into the lower part of the fluidized bed, the hydrogen chloride was mixed with heated silicon tetrachloride and hydrogen and put into the lower part of the gas dispersion plate. When hydrogen chloride was introduced into the upper part of the fluidized bed, 98% height of the total height of the layer). After the addition of the reactants, the reaction product was analyzed by a gas chromatograph (TCD detector) connected on-line at the top of the reactor in a period of 35 minutes. The reaction product was reacted for 2 hours according to the reaction conditions, Table 1 shows the results.

As can be seen from Table 1, the greater the amount of hydrogen chloride introduced and the greater the amount of hydrogen chloride introduced into the reactor fluidized bed, the greater the amount of trichlorosilane produced.

[ Example 4 to 8]

The reaction was prepared in the same manner as in Examples 1 to 3 to examine the influence of the trichlorosilane conversion rate of hydrogen chloride on the temperature, the input position and the reactant retention time. Only hydrogen chloride was added without introducing silicon tetrachloride, and nitrogen, which is an inert gas, was added together to control the reaction heat and the residence time. The reaction temperature, the injection position and the residence time were changed as shown in Table 2, and the reaction products after the addition of the reactants were analyzed in the same manner as in Examples 1 to 3 and shown in Table 2 below.

As can be seen from Table 2, it can be seen that the shorter the residence time of hydrogen chloride in the reaction layer, the lower the reaction temperature, and the greater the amount added to the upper portion of the fluidized bed, the greater the amount of trichlorosilane produced.

[ Example 9 and 10]

In order to investigate the influence of the temperature of the free board on the upper part of the reactor which is outside the fluidized bed when the hydrogen chloride is injected into the upper part of the fluidized bed, the experiment was carried out in the same manner as in Example 3 except for the temperature of the free space of the reactor. . The reaction products after the addition of the reactants were analyzed in the same manner as in the previous examples and shown in Table 3 below.

As can be seen from Table 3, it was confirmed that the amount of trichlorosilane produced increased as the temperature of the free space in the reactor was lowered when hydrogen chloride was introduced into the upper portion of the fluidized bed.

[ Example 11]

In the case of introducing hydrogen chloride into the upper part of the fluidized bed, H2 injection to the free board on the free space of the reactor to examine the influence of the trichlorosilane conversion rate through the H2 quenching for controlling the temperature of the free space above the reactor, The experiment was carried out in the same manner as in Example 3. The reaction products after the addition of the reactants were analyzed in the same manner as in the previous examples and shown in Tables 4 and 5 below.

As can be seen from Tables 4 and 5, when the hydrogen chloride was introduced into the upper portion of the fluidized bed, H2 was injected into the space above the reactor to lower the temperature of the free board section of the reactor through the quenching effect. . In H2 quenching, not only the temperature reduction effect of the free board on the upper part of the reactor but also the residence time of the reaction product is reduced to minimize the conversion of the generated trichlorosilane to the tetrachlorosilane by the reverse reaction, thereby further increasing the conversion rate of the trichlorosilane .

[ Example 12]

In order to investigate the effect of chlorosilane (quartsil silane) quenching for controlling the temperature of the free board on the upper part of the reactor beyond the fluidized bed, ) Was carried out in the same manner as in Example 3, except that chlorosilane was added. The reaction products after the addition of the reactants were analyzed in the same manner as in the previous examples and are shown in Tables 6 and 7 below.

As can be seen from Tables 6 and 7, when the hydrogen chloride was fed into the upper portion of the fluidized bed, the temperature of the free board zone above the reactor was lowered through quenching by injecting the tetrachlorosilane into the space above the reactor, . In addition to the temperature reduction effect of the free board on the upper part of the reactor during chlorosilane quenching, it is also expected to reduce the residence time of the reaction product to minimize the conversion of the generated trichlorosilane to the tetrachlorosilane by the reverse reaction, thereby further increasing the conversion of trichlorosilane can do.

1: Heater for heating the superheater, raw material (H ₂ + STC)
2: Fluidized Bed Reactor Gas Dispersion Plate
3: Fluidized Bed Reactor Reaction Layer (MG Si bed)
4: Fluidized Bed Reactor (FBR)
5: Free space above the fluidized bed reactor (Free Board)
6: Cyclone (The silicon fine powder contained in the reaction product is separated and re-introduced into the reactor
MG Si: Metallic Silicon
STC: Silicon Tetrachloride
TCS: Trichlorosilane
Crude TCS: an unpurified chlorosilane mixture containing TCS
Purified TCS: High purity TCS with impurities removed
Polysilicon: Polycrystalline Silicon, final product
Separation: High boiling point impurities included in the reaction product, chlorosilane and H ₂ gas separation
Purification: separation of chlorosilane mixture through distillation column, purification
Reduction: Manufacture of polysilicon through CVD (Chemical Vapor Deposition)
Off-gas recovery: Recovery of H ₂ , HCl, and chlorosilanes from CVD reactions

Claims

A first step of filling the reactor with a metallic silicon reaction layer and a catalyst;
A second step of producing trichlorosilane by supplying silicon tetrachloride and hydrogen to the reactor; And
And a third step of producing trichlorosilane by supplying chlorine, hydrogen chloride, or a mixture thereof to a region at or above a point 70% of the total height of the metallic silicon reaction layer in the reactor.

The process for producing trichlorosilane according to claim 1, wherein the reaction temperature in the second stage is 400 to 700 ° C and the reaction pressure is 1 to 40 barg.

The process according to claim 1, wherein in the second step, 1 to 10 moles of hydrogen is supplied per mole of silicon tetrachloride.

The process for producing trichlorosilane according to claim 1, wherein the residence time of chlorine, hydrogen chloride or a mixture thereof is 0.01 to 100 seconds.

The method of claim 1, wherein in the third step, 0.01 to 10 moles of hydrogen chloride, chlorine, or a mixture thereof is supplied per mole of silicon tetrachloride.

The method according to claim 1, wherein the recovered silicon tetrachloride, hydrogen, and hydrogen chloride are supplied as a byproduct of the polycrystalline silicon production process as a reactant.

The method of claim 1, further comprising: supplying hydrogen, a liquid silicon tetrachloride or chlorosilane mixture cooled to -20 to 50 占 폚 to the free space in the reactor; Or cooling the free space in the reactor to 100 to 500 占 폚 using a heat exchanger.

The process according to claim 7, wherein the amount of the cooled hydrogen, liquid silicon tetrachloride or chlorosilane mixture is 0.5 to 10 moles per mole of silicon tetrachloride in the second stage.

The method according to claim 1, wherein, in the third step, chlorine, hydrogen chloride, or a mixture thereof is supplied to a region at or above 90% of the total height of the metallic silicon reaction layer to produce trichlorosilane Way.