KR20190090927A - Method for purifying hexachlorodisilane - Google Patents

Abstract

The present invention relates to a method for purifying hexachlorodisilane. The method for purifying hexachlorodisilane according to the present invention has an effect of separating and recovering hexachlorodisilane with a high purity from various kinds of metal impurities, including aluminum and titanium, even in a relatively simple process.

Description

Method for purifying hexachlorodisilane {Method for purifying hexachlorodisilane}

The present invention relates to a method for purifying hexachlorodisilane.

Hexachlorodisilane (HCDS) is a useful compound throughout the industry, used as an important starting material in microelectron optics. Such compounds are used in particular as precursors in chemical vapor deposition (CVD) for high purity silicon nitride layers, silicon oxide layers or silicon carbide layers. Hexachlorodisilane also plays an important role during transistor fabrication in memory chips.

Hexachlorodisilane is usually made from silicides, and hexachlorodisilane thus prepared is poor in purity, including trace amounts of titanium and other metal impurities. Titanium, which is one of the metal impurities, may be present by forming titanium chloride (IV), and since titanium (IV) has a boiling point similar to that of hexachlorodisilane, it is difficult to be removed by a simple distillation method. Complex fractional distillation is therefore usually used, but the purification efficiency is still poor. In addition to titanium, various metal impurities are not separated in the distillation process and have a problem of being obtained with hexachlorodisilane.

Therefore, in order to increase the purification efficiency, a distillation process having a large number of separation steps is conventionally used, which is very disadvantageous in terms of energy and technology. In addition, the yield of the final purified hexachlorodisilane is low, there is a problem that the equipment and safety-related costs are increased.

Korean Patent Publication No. 10-2011-0061594 discloses a method for removing titanium from hexachlorodisilane in order to solve the above problem. However, in this patent, the final purified product containing hexachlorosilane contains titanium or titanium compounds of up to 50 ppb (wt) or more, which still limits purification efficiency and is effective in removing other kinds of metal impurities. There is no problem.

Therefore, there is a need for a method of removing various kinds of metal impurities and purifying hexachlorodisilane with higher purity.

Korean Patent Publication No. 10-2011-0061594 (2011.06.09)

It is an object of the present invention to provide a method for purifying hexachlorodisilane, which is capable of separating and recovering hexachlorodisilane in high purity from various kinds of metal impurities, including aluminum and titanium, even in a relatively simple process.

The method for purifying hexachlorodisilane according to the present invention comprises the steps of: a) controlling the water content of the ion exchange resin, b) reacting the purified object comprising the ion exchange resin and hexachlorodisilane having the water content controlled. C) separating and obtaining hexachlorodisilane by fractional distillation of the reaction product obtained in step b), d) crystallizing metal impurities by allowing the obtained hexachlorodisilane to stand at low temperature, and e) Filtering the low temperature hexachlorodisilane.

In one embodiment of the present invention, the ion exchange resin may be a styrene-based chelate resin containing a carboxylate group.

In one example of the present invention, step a) may be a step of controlling the water content of the ion exchange resin to 1.2 wt% or less through drying.

In one embodiment of the present invention, the reaction of step b) may be carried out at room temperature or less.

In one embodiment of the present invention, the reaction of step b) may be carried out for 0.5 to 24 hours.

In one embodiment of the present invention, step b) may include mixing the water exchange controlled ion exchange resin and the purified object, the ion exchange resin is 10 to 100 parts by weight of the purified object To 100 parts by weight.

In one example of the present invention, the fractional distillation of step c) may be secondary distillation after the first distillation, the pressure during the first distillation may be less than the pressure during the second distillation.

In one example of the present invention, the primary distillation may be performed at 10 torr or less, and the secondary distillation may be performed at 100 to 500 torr.

In one embodiment of the present invention, in step d), the stationary temperature may be 5 ℃ or less.

In one embodiment of the present invention, in step d), the settling time may be 0.5 to 3 hours.

In one embodiment of the present invention, in step e), the filtration may be performed using a filter having an average pore of 450 nm or less.

Purification method of hexachlorodisilane according to the present invention Even in a relatively simple process, it is possible to separate and recover hexachlorodisilane with high purity from various kinds of metal impurities including aluminum and titanium.

Even if the effects are not explicitly mentioned in the present invention, the effects described in the specification and the inherent effects expected by the technical features of the present invention are treated as described in the specification of the present invention.

Hereinafter, the method for purifying hexachlorodisilane according to the present invention will be described in detail.

Unless otherwise defined in the technical and scientific terms used in the present invention, those having ordinary skill in the art to which the present invention belongs have the meanings that are commonly understood, and the gist of the present invention is unnecessary in the following description. Descriptions of well-known functions and configurations that may be blurred are omitted.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

 The unit of% used without special mention in the present invention means weight% unless otherwise defined.

"Alkyl" as described herein means a monovalent hydrocarbon chain comprising carbon and hydrogen, which hydrocarbon chain may be branched or straight chain, preferably straight chain.

The method for purifying hexachlorodisilane according to the present invention comprises the steps of: a) controlling the water content of the ion exchange resin, b) reacting the purified object comprising the ion exchange resin and hexachlorodisilane having the water content controlled. C) separating and obtaining hexachlorodisilane by fractional distillation of the reaction product obtained in step b), d) crystallizing metal impurities by allowing the obtained hexachlorodisilane to stand at low temperature, and e) Filtering the low temperature hexachlorodisilane.

The metal impurity referred to in the present invention may include a metal element, a compound combined with a metal element, or the like, and the metal element and the compound refer to all materials that can be obviously interpreted as impurities in the art. Specific examples thereof may include Al, Ti, Fe, Ni, Cr, Zn, Na, K, Pb, As, Ca, Co, Mg, Mn, Ni, and the like. Should not be.

The ion exchange resin may be preferably a styrene chelate resin including a carboxylate group, specifically, a styrene chelate resin in which a carboxylate group is repeatedly bonded to a main chain in terms of more effectively removing metal impurities. In this case, the salt of the carboxylate group may be a known metal atom used in a chelate resin such as a Group 1 metal such as Na or a Group 2 metal. Specifically, when hexachlorodisilane is purified through each step according to the present invention using the chelate resin, metal impurities including titanium and aluminum, which are generally not easy to remove, may be effectively removed. In addition, metal impurities other than aluminum and titanium can be effectively removed.

The chelate resin may proceed through a substitution reaction when reacted with metal impurities. For example, chlorine is substituted with a metal salt of the chelate resin from titanium chloride or aluminum chloride to dissociate metal impurities, or titanium chloride. Alternatively, a reaction may be performed in which titanium or aluminum is substituted with the metal salt of the chelate resin from aluminum chloride. Through this reaction, metal impurities are bound to the ion exchange resin or dissociated by the ion exchange resin, and then removed through a distillation step and a filtration step.

As a specific example, the carboxylate group may be a (C1-C5) alkylamino (C1-C5) alkylcarboxylate group, and in more specific embodiments, may be represented by the chemical formula 1, but this is only a preferred example. Of course, the present invention is not limited thereto.

[Formula 1]

In this case, in order to prevent side effects in which hexachlorodisilane is consumed by reacting with water, the ion exchange resin should have a controlled water content. If the water content of the ion exchange resin is not controlled, by-products such as silicon dioxide generated by side reaction of hexachlorodisilane with a large amount of water lose the meaning of purifying hexachlorodisilane.

That is, the moisture content of the ion exchange resin should be reduced through the moisture content control step of step a), and preferably reduced below a specific content. As a specific example, step a) is to control the water content of the ion exchange resin in the range of 1.2% by weight or less, 1.0% by weight or less, specifically 0.01 to 1.2% by weight, 0.01 to 1.0% by weight through drying. It may be desirable. The water content of the ion exchange resin is adjusted to 1.2 wt% or less, and when reacting in step b), the purity of the final purified hexachlorodisilane may be significantly increased. However, this is only a preferred example, and the present invention is not limited thereto.

As a method of controlling the moisture content, a drying process may be exemplified, and various drying methods such as natural drying, hot air drying, convection drying, and vacuum drying may be used, and the method may be used as long as it can control the moisture content.

The temperature of the reaction of step b) is not particularly limited, but may be preferably performed at room temperature or less. If this is satisfied, it is possible to prevent the problem of reacting violently by too high temperature and the problem of lowering the reaction efficiency by too low temperature, and to induce an efficient reaction to increase the purity of the final purified hexachlorodisilane. have. However, this is only a preferred example, and the present invention is not limited thereto.

The reaction time of step b) may be sufficient as long as the reaction can proceed sufficiently, for example, 0.5 to 24 hours, 0.5 to 10 hours, but the present invention is not limited thereto.

The reaction method of step b) may be such that the ion exchange resin and the purified object to contact. Specifically, step b) may include mixing the water exchange controlled ion exchange resin and the purified object. In this case, the mixing ratio may be appropriately controlled so that the unreacted substance is not present. For example, the ion exchange resin may be mixed in an amount of 10 to 100 parts by weight based on 100 parts by weight of the purified object, but the present invention is not limited thereto. .

The mixture including the ion exchange resin, hexachlorodisilane, and metal impurities in which the reaction is completed may separate and recover hexachlorodisilane through the distillation process of step c). The distillation process may be single-stage distillation or multistage distillation. As a specific example, fractional distillation of step c) may be preferably secondary distillation after primary distillation. In this case, the pressure at the first distillation may be smaller than the pressure at the second distillation. As a specific example, the first distillation may be carried out at a pressure of 10 torr or less, specifically 0.1 to 10 torr, the second distillation may be carried out at a pressure of 100 to 500 torr, but this is only a preferred example, Of course, the present invention is not limited thereto.

The distillation temperature may be appropriately adjusted to be able to separate and recover the hexachlorodisilane through distillation, which is not limited because the skilled person can perform the process under appropriate control depending on the pressure described above.

In the present invention, step d) is a step of effectively separating metal impurities and separating and recovering high-purity hexachlorodisilane, which is an important step in which most metal impurities can be removed. Even if the hexachlorodisilane is separated and recovered through the distillation of step c), the metal impurities are present in large quantities above the required level of 20 ppb (wt). Therefore, hexachlorodisilane can be purified in high purity, for example, with a metal impurity content of 0.5 ppb (wt) or less through filtration in step e) through the crystallization of metal impurities in step d). At this time, the stationary temperature, that is, the crystallization temperature is an important factor for the crystallization of the metal impurities, the crystallization does not proceed properly at room temperature of 25 ℃ or more does not significantly improve the purification efficiency. Therefore, the settling temperature of step d) is a low temperature, specifically, 5 ° C or less, 3 ° C or less, where the lower limit may be the freezing point of hexachlorodisilane, and more specifically, may be -1 to 5 ° C.

In step d), the settling time may be sufficient to sufficiently crystallize the metal impurities. For example, 0.5 to 3 hours may be preferable in terms of sufficient crystallization, side reaction prevention, and process efficiency increase, but the present invention is not limited thereto. Of course not.

In step e), the filtration may be any one capable of filtering the crystallized metal impurities. As a specific example, the filtration may be preferably performed using a filter having an average pore of 450 nm or less, specifically, 10 to 450 nm, because it can effectively filter crystallized metal impurities, but the present invention is not limited thereto. Of course.

Hereinafter, the present invention will be described in detail with reference to Examples, but these are for explaining the present invention in more detail, and the scope of the present invention is not limited by the following Examples.

An ion exchange resin (Diaion ^R CR11, Mitsubishi Chemical), a chelate resin having carboxylate groups, was placed in a convection oven and dried first at 60 ° C. The first dried ion exchange resin was placed in a vacuum oven and dried secondly at 70 ° C. to obtain an ion exchange resin having a water content of 1.2 wt% or less.

After cooling 1 kg of hexachlorodisilane object containing various kinds of metal impurities described in Table 1 to 0 ° C. in a nitrogen atmosphere, 0.35 kg of the obtained ion exchange resin in a nitrogen atmosphere and room temperature (25 ° C.) It was mixed with the hexachlorodisilane object and reacted for 1 hour.

Fe Cu Ni Cr Zn Na K Pb 15.523 1.694 67.048 4.638 8.657 0.186 0.061 0.029 Ti As Ca Co Mg Mn Al 6.285 0.008 0.957 0.027 0.056 0.596 30000.000 Unit: ppb (wt)

The obtained product including the reaction product of which the reaction was completed was subjected to first low temperature distillation, and then subjected to second fractional distillation to obtain a mixture containing high purity hexachlorodisilane. At this time, the first low temperature distillation was carried out by gradually increasing the temperature to 30 ~ 60 ℃ while maintaining a pressure of 0.3 torr. In addition, the second fractional distillation was performed by gradually increasing the pressure from 60 to 78 ° C. in the initial tank and from 80 to 83 ° C. in the main tank while maintaining a pressure of 250 torr.

The yield immediately after the completion of the first distillation was 84%, 67% after the completion of the second distillation.

As soon as the second distillation was completed, the mixture containing hexachlorodisilane obtained immediately was allowed to stand at 0 ° C. for 1 hour to crystallize metal impurities.

And the mixture was left to filter with a syringe filter (0.45 ㎛ or less) (syringe filter) to separate and obtain hexachlorodisilane.

Comparative Example 1

In Example 1, the mixture containing hexachlorodisilane obtained immediately after the completion of the second distillation is left without standing to crystallize the metal impurities, and filtered with a syringe filter of 0.45 μm or less, and then hexachloro. Hexachlorodisilane was isolated and obtained in the same manner as in Example 1 except that the disilane was separated and obtained, i.e., without undergoing the step of crystallization of the stationary and metal impurities.

Comparative Example 2

In Example 1, the mixture containing hexachlorodisilane obtained immediately after the completion of the second distillation was left at 0 ° C to crystallize the metal impurity, instead of crystallizing the metal impurity to crystallize the metal impurity. Except that, hexachlorodisilane was isolated and obtained in the same manner as in Example 1.

Comparative Example 3

In Example 1, except that the water content of the free exchange resin was not controlled, i.e., the water content of 50% by weight of water instead of the controlled ion exchange resin of 1.2% by weight or less was not controlled. Hexachlorodisilane was isolated and obtained in the same manner as in Example 1 except that the resin was reacted with the hexachlorodisilane object.

Purity Assessment of Purified Hexachlorodisilane

In order to evaluate the purity of the final purified hexachlorodisilane in Example 1, Comparative Examples 1 to 3, the content of metal impurities contained in the obtained product containing each final purified hexachlorodisilane was measured. The results are shown in Table 2 below. In this case, as the measurement metal type, aluminum (Al) and titanium (Ti), which are conventionally known to be more difficult to remove than other types of metals, were measured. As a measuring method, inductively coupled plasma mass spectrometry (ICP-MS) was used.

ppb (wt) Control Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Al 30000.000 0.391 20.000 17.381 - Ti 6.285 0.091 4.260 5.918 - Control group: Hexachlorodisilane object containing various kinds of metal impurities without purification process

As can be seen from Table 2, in the removal of aluminum metal impurities, Comparative Example 1, which did not undergo metal crystallization, was removed at 20 ppb or more, whereas Example 1, which had undergone metal crystallization, was less than 0.4 ppb. It was removed to a very high level. In addition, in the removal of titanium metal impurities, Comparative Example 1 without metal crystallization was removed to 4.2 ppb or more, whereas Example 1 after metal crystallization was removed to a very high level of less than 0.1 ppb. This is believed to be due to the crystallization and growth of more than a certain size so that the metal impurities present in the mixture upon standing can be properly filtered in the subsequent filtration process.

In addition, even if the metal crystallization through the stationary, as in Comparative Example 2, when the metal crystallization at room temperature, not low temperature, compared with the case of Example 1, the purity improvement due to the metal crystallization is insignificant from Table 2 You can check it.

In addition, as in the case of Comparative Example 3, when the moisture content of the ion exchange resin is not controlled, it is impossible to measure impurities as hexachlorodisilane reacts with a large amount of water to produce byproducts such as silicon dioxide. The purification of hexachlorodisilane itself was meaningless.

In addition, although not shown in Table 2, in Example 1, in addition to Al and Ti metal impurities, Fe, Ni, Cr, Zn, Na, K, Pb, As, Ca, Co, Mg, Mn, Ni, etc. It was confirmed that the metal impurities of were also purified with very high efficiency.

Claims (11)

a) controlling the moisture content of the ion exchange resin
b) reacting the purified object including the ion-exchange resin and hexachlorodisilane having the moisture content controlled;
c) separating and obtaining hexachlorodisilane by fractional distillation of the reaction product obtained in step b).
d) low temperature hexachlorodisilane obtained to crystallize the metal impurities; and
e) filtering the low temperature hexachlorodisilane
Method for purifying hexachlorodisilane comprising a. The method of claim 1,
The ion exchange resin is a method for purifying hexachlorodisilane which is a styrene chelate resin containing a carboxylate group. The method of claim 1,
The step a) is a step of controlling the water content of the ion exchange resin to 1.2 wt% or less through drying method of hexachlorodisilane. The method of claim 1,
Reaction step of step b) is carried out at room temperature or less purification method of hexachlorodisilane. The method of claim 1,
The reaction of step b) is a purification method of hexachlorodisilane is carried out for 0.5 to 24 hours. The method of claim 1,
Step b) includes mixing the moisture exchanged ion exchange resin and the purified object,
A method for purifying hexachlorodisilane, wherein the ion exchange resin is mixed in an amount of 10 to 100 parts by weight based on 100 parts by weight of the purified object. The method of claim 1,
Fractional distillation of step c) is secondary distillation after primary distillation,
The pressure in the first distillation is less than the pressure in the second distillation method of purifying hexachlorodisilane. The method of claim 7, wherein
The first distillation is carried out at 10 torr or less,
The second distillation is a method for purifying hexachlorodisilane is carried out at 100 to 500 torr. The method of claim 1,
In the step d), the stationary temperature is 5 ° C or less purification method of hexachlorodisilane. The method of claim 1,
In step d), the settling time is 0.5 to 3 hours, the purification method of hexachlorodisilane. The method of claim 1,
In the step e), the filtration is carried out using a filter having an average pore of 450 nm or less.