JP2967397B2 - Purification method of alkoxyarsine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying alkoxyarsine for removing chlorine compounds as impurities contained in alkoxyarsine. More specifically, the present invention relates to a method for purifying an alkoxyarsine, which comprises adding an alkali metal alkoxide or an alkaline earth metal alkoxide, stirring, and then distilling the alkoxyarsine during distillation purification.

[0002]

It is already known that alkoxyarsine is produced from the reaction of arsenic trioxide with an alcohol or the reaction of arsenic trichloride with an alcohol and ammonia.

[0003] In recent years, in a process of manufacturing an VLSI, a silica-based coating liquid for diffusing arsenic into a silicon wafer (for example, JP-A-3-11624) or an arsenic oxide which is excellent in step coverage by CVD. -In order to form a silica glass film (for example, JP-A-1-286319) and the like, high-purity alkoxyarsine containing no chlorine or metal impurities is required. Especially for chlorine,
In order to promote the corrosion of the circuit, it is required that the content be reduced to the order of ppm or less.

However, since alkoxyarsine has not been used in the production of VLSI,
There is no report on a method for producing and purifying high-purity alkoxyarsine suitable for this purpose and a method for quantitatively analyzing a trace amount of chlorine contained in alkoxyarsine.

Therefore, the present inventors distilled the alkoxyarsine synthesized by the reaction of arsenic trichloride, alcohol and ammonia, and analyzed the chlorine content as an impurity in the main fraction. And turned out to be very much.

In the analysis method, alkoxyarsine was hydrolyzed, chlorine in the produced slurry was quantified by potentiometric titration, and metal impurities were quantified by ICP emission spectrometry.
The analysis in the examples also used the above-mentioned analysis method. Although not chlorine compounds in the alkoxy arsine identification is, many _{As (OR) x Cl y (} OR is an alkoxy group, x + y = 3) is presumed to be present, the only part of ammonium chloride or trichloride Considered to be arsenic.

[0007]

In the prior art for producing alkoxyarsine by the reaction of arsenic trichloride, alcohol and ammonia, several hundred ppm are contained in alkoxyarsine.
It is unavoidable that chlorine is contained as an impurity in the aluminum alloy. In addition, when a small amount of chlorine is contained in the alkoxyarsine produced by the reaction of arsenic trioxide and alcohol, it is impossible to reduce the chlorine to less than ppm order by conventional techniques such as distillation. It is.

It is an object of the present invention to provide a method for purifying alkoxyarsine in which the chlorine content in the alkoxyarsine is reduced to the order of ppm or less.

[0009]

Means for Solving the Problems The present inventors have been studying synthesis reactions of metal alkoxides for many years.
In addition, we have been studying the purification method. As a result, it has been found that chlorine content can be efficiently reduced by adding and stirring an alkali metal alkoxide or an alkaline earth metal alkoxide when distilling and refining alkoxyarsine, thereby completing the present invention.

That is, a feature of the present invention is that when an alkoxyarsine is purified by distillation, an alkali metal alkoxide or an alkaline earth metal alkoxide is added and stirred.
It is then distilled.

The added alkali metal or alkaline earth metal reacts with chlorine to remain in the liquid as chlorides. These chlorides and unreacted alkali metal alkoxides and alkaline earth metal alkoxides are non-volatile. Since it is a compound, it can be easily separated from alkoxyarsine by distillation. Therefore, the chlorine content contained in the alkoxyarsine can be removed to the order of ppm or less.

The alkoxyarsine in the present invention may be any as long as it can be distilled. Preferably, the alkoxyarsine is trimethoxyarsine, triethoxyarsine, tripropoxyarsine, triisopropoxyarsine, tributoxyarsine, triisobutoxyarsine, triisobutoxyarsine or triisoaroxy. Tertiary butoxyarsine and trisecondary butoxyarsine.

The alkali metal alkoxide or alkaline earth metal alkoxide used in the present invention is
Sodium methoxide, sodium ethoxide, sodium propoxide, sodium isopropoxide, potassium methoxide, potassium ethoxide, potassium propoxide, potassium isopropoxide, lithium methoxide, lithium ethoxide, lithium propoxide, lithium isopropoxide , Magnesium methoxide, magnesium ethoxide, magnesium propoxide, magnesium isopropoxide, calcium methoxide, calcium ethoxide, calcium propoxide, calcium isopropoxide, strontium methoxide, strontium ethoxide, strontium propoxide, strontium isopropoxy And so on.

The above compound is used in an amount equal to or greater than the reaction equivalent of chlorine contained in the alkoxyarsine, preferably from 3 to 3 equivalents.
What is necessary is just to add 5 times the amount. When water is contained in the alkoxyarsine, these compounds react with water and disappear, and thus may be added in an amount equal to or more than the water equivalent, preferably 3 to 5 times.

In the present invention, the addition of an alkali metal alkoxide or an alkaline earth metal alkoxide is performed in an inert gas atmosphere so as to prevent water from entering, and the liquid temperature is maintained at 30 ° C. to 80 ° C. for about 1 hour while stirring. Just fine.

The alkoxyarsine used in the present invention is produced by a process for removing by-product ammonium chloride crystals from a reaction product of arsenic trichloride, alcohol and ammonia by a mechanical operation such as filtration or centrifugation. Is preferred. That is, the arsenic trichloride raw material used in this production method can be easily purified by distillation, so that other metal impurities can be extremely reduced, and the metal impurities in alkoxyarsine can be reduced. That's why.

Hereinafter, embodiments of the present invention will be described in detail.
Needless to say, the following embodiments are merely examples of the present invention, and the present invention is not limited to these embodiments.

[0018]

Example 1 Into a four-necked flask equipped with a stirrer and a condenser and replaced with argon, dehydrated toluene 61 and 1,733 g (37.6 mol) of dehydrated ethanol were charged, and 2168 g (11.96 g) of anhydrous arsenic trichloride was stirred with stirring. Mol) was added, and ammonia gas 9001 (40.2 mol) was blown in over 6 hours while cooling the flask. During this time, the reaction temperature was maintained at 30 to 50 ° C.

The product was filtered to remove by-product ammonium chloride crystals, 7 g of sodium ethoxide was added to the filtrate, and the mixture was heated and stirred at 50 ° C. for 1 hour. Then, after ethanol and toluene were distilled off under normal pressure, simple distillation was performed at 100 Torr to obtain crude triethoxyarsine.

This is charged in a rectifying kettle, and 10
Distillation under reduced pressure of 0 Torr was performed to obtain 2140 g of colorless and transparent pure triethoxyarsine as a main fraction at around 107 ° C. (yield: 85%). When this purified triethoxyarsine was analyzed, the chlorine content was 1 ppm and the sodium content was 1 ppm.
It was below.

[0021]

Example 2 15 g of strontium isopropoxide was used instead of sodium ethoxide used in Example 1.
A main fraction was obtained by performing the same operation as in Example 1 except that was used. The analysis values were 2 ppm for chlorine and 1 ppm or less for strontium.

[0022]

Comparative Example A main fraction was obtained in the same manner as in Example 1 except that sodium ethoxide was not added. The analysis value was 240 ppm of chlorine and 1 ppm or less of sodium.

[0023]

According to the present invention, an alkoxyarsine having an extremely small amount of chlorine reduced by adding an alkali metal alkoxide or an alkaline earth metal alkoxide, stirring and then distilling the same when distilling and purifying the alkoxyarsine. Has the characteristic that it can be obtained in good yield.
When distillation was performed without adding an alkali metal alkoxide or an alkaline earth metal alkoxide to alkoxyarsine as in the comparative example, the chlorine content was as high as several hundred ppm, and pp
Cannot be refined to the order of m. On the other hand, according to the present invention, as is clear from the examples, the chlorine content can be purified to the order of ppm or less.

Claims (2)

(57) [Claims] 1. A process for purifying an alkoxyarsine by distillation.
A method for purifying alkoxyarsine, comprising adding an alkali metal alkoxide or an alkaline earth metal alkoxide, stirring, and then distilling. 2. The method according to claim 1, wherein the alkoxyarsine is trimethoxyarsine, triethoxyarsine, tripropoxyarsine, triisopropoxyarsine, tributoxyarsine, triisobutoxyarsine, tritertiary butoxyarsine, or trisecondary butoxyarsine. The method for purifying alkoxyarsine according to claim 1, wherein