JPS61197415A - Purification of dichlorosilane - Google Patents

Abstract

PURPOSE:To obtain a high-purity dichlorosilane, with simple apparatus and operation, in high efficiency, by contacting a nitrilesupporting high-silica zeolite with gaseous dichlorosilane, thereby removing the boron compounds from the dichlorosilane. CONSTITUTION:SiH2Cl2 is discharged from the bomb 1 in gaseous state, controlled to a specific flow rate by the mass flow-controller 2, and introduced into the absorption column 4 packed with high-silica zeolite 3 supporting a nitrile. The boron compounds existing in the SiH2Cl2 as impurities are adsorbed and removed in the absorption column 4, and the obtained high-purity SiH2Cl2 gas is passed through the line filter 5, and condensed and collected in the collector 8 and the recovering device 9 cooled with the freezing mixture. At the start of the operation, the line is substituted with an inert gas such as N2, etc., and the outlet line 8a is supplied constantly with an inert gas 10 during the operation. A high-purity SiH2Cl2 useful as a raw material for the production of semiconductor silicon can be produced by this process.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for purifying dichlorosilane, and more specifically, to a method for purifying dichlorosilane by removing boron compounds, particularly boron trichloride, from dichlorosilane. The present invention relates to a method for producing dichlorosilane to obtain pure dichlorosilane.

[Conventional technology]

Dichloro7 used as a raw material for manufacturing semiconductor silicon
The orchid is required to be highly pure, and if it contains a boron compound, even a very small amount, it will adversely affect the electrical performance of semiconductor silicon.

Conventionally, dichlorosilane (hereinafter referred to as 31)1. To remove boron compounds from (denoted as α, ), (tlsiH.

Distillation method by adding various boron compound scavengers to C6 (Japanese Patent Publication No. 46-22755. U-8-P-31
26248), (method of contacting with 2J water and then steaming), Japanese Patent Publication No. 56-32247. DD-P-155615
1, (31 Method of adsorption with adsorbent (GB-P-895)
495) etc.

StH, C6, has a boiling point of a2°C and spontaneously ignites when exposed to air, so it cannot be handled in an open system.

Therefore, the equipment for the distillation method in (1) is a pressurized closed system, which is complicated, requires corrosion resistance, and is expensive because it uses high-grade stainless steel or a material with a special surface treatment. If the residue is left in the pot, there are problems such as product contamination due to K.

In addition, method (2;) utilizes the instantaneous reaction of boron trichloride (Begs) with water, but the above rl
)of,! ! In addition to the shortcomings of the distillation method, RIQsilanes are also hydrolyzed when they come into contact with water, which not only causes losses, but also generates H(l) through hydrolysis, which coexists with water and is extremely corrosive. This is extremely troublesome because the hydrolysis products of chlorosilanes (called polysiloxanes) clog the equipment and can only be dissolved with concentrated NaOH.(3) Adsorption The method is to support an organic substance that reacts with boron chloride on activated carbon, silica gel, or the like, and then pass silane or chlorinated silane containing a boron compound in contact with the organic substance.

However, when used to remove boron compounds in s S i $ Cel, when activated carbon is used as a carrier, a large amount of unknown components are produced, and when silica gel is used, a large amount of HCe is produced.

Furthermore, these documents describe devices that cannot be used for substances that have a low boiling point and ignite when exposed to air.

[Problem to be solved by the invention]

Hanmei aims to solve the above-mentioned problems and provide an 81M method for dichlorosilane, which does not generate solid decomposition products or HCJ and removes boron compounds using a simple device and easy operation.

[Means for solving problems]

The present invention has been made to achieve the above objects,
The gist of this method is to develop a method for purifying dichlorosilane by bringing dichlorosilane into contact with a high silica zeolite carrying nitrile in a gas phase to remove the boron compounds contained therein.

[For production]

The method according to the present invention uses Si
Since high silica zeolite, which is inert to H, (Jl) and has high adsorption power, is used, SIH and CIN do not decompose, and boron compounds can be efficiently removed at room temperature and pressure. .

[Specific structure of the invention]

The method for purifying S1 C# according to the present invention will be described below with reference to the drawings.

The first figure shows an example of an apparatus for carrying out the method of the present invention, and the reference numeral 1 in the figure is a cylinder containing 5IH1 (Jt). After passing through the controller 2, it is guided to an adsorption column 4 filled with isilica zeolite 3 (which has a predetermined flow rate and supports nitrile), and the boron compounds contained therein are adsorbed and removed. High purity S1.ICI.

After passing through the line filter 5, the gas passes through a collector 67 and a collector 8, each cooled by a cryogen 6, and is condensed and collected as high-purity 51H1C1119. The above operation is performed at the start after replacing the inside of the line with an inert gas such as N2, and during operation, the outlet line 8 &
Inert gas 1O is constantly introduced into the system to prevent air from flowing back into the equipment line. Note that 11 in the figure is a pressure indicator, and the system should be operated at room temperature.

In this method, the nitrile that reacts with boron trichloride to become a nonvolatile substance is a common nitrile, such as acetonitrile, propionitrile, butyronitrile, valeronitrile, capronitrile.

Accuronitrile, chloroacetonitrile, benzonitrile, fueruasatonitrile, P-Me? Lupenzonitrile, P-methoxybenzonitrile, P-rir: 10
These include benzonitrile, P-nitrobenzonitrile, phthalonitrile, iso7talonitrile, succinonitrile, geltalonitrile, adiponitrile, and any of them can be used effectively.

Moreover, high silica zeolite refers to a zeolite with an S1/A4 (% ratio, the same hereinafter) larger than 1.5. S
t/Ag: 17-1.2 deaf zeolite, Si/AI
The X-type zeolite with l:1 to 1.5 is 8iH, (J.

It cannot be used because it is acidic and the crystal structure is destroyed.

Examples of high-silica zeolite include Y-type zeolite: I-niji/Ag: 1.5-3, Union Showa JE-15
P Si, /A41:AM, /-)Y company 111 Zeo a
:i St/Ag: 5, Moldemit manufactured by Toyo Soda
+s-based TSZ Si/Ad:9.3, etc. are commercially available.In order to support nitrile on high-silica zeolite, a general method is to immerse the high-silica caseolide in a solution in which nitrile is dissolved in a solvent, and then remove the solvent. It will be held in

However, 31)(t (J'
When it comes into contact with t, it decomposes and generates HCl, and the pipes are clogged by the solids.

At this time, if a high silica zeolite is supported on a nitrile and then completely dehydrated, a portion of the supported nitrile will volatilize, so the solvent and the high silica zeolite must be completely dehydrated and dried.

Although acetone is a good solvent for nitriles, it easily absorbs water, so even if it is sufficiently dehydrated in advance, it will absorb water again during the supporting operation. Therefore, as the solvent, chlorinated hydrocarbons that are insoluble in water, such as chloroform, methylene chloride, carbon tetrachloride, dichloroethane, and trichloroethylene, are preferably used.

In dichlorosilane, the boron compound is boron trichloride (B(
1,). B(1, is Ha p knee 10
7°C, bp: 12.5°C and the boiling point is 5111. The concentration in the gas obtained by vaporizing 81H2Cgt in a cylinder, which is close to C6°, is almost the same as the concentration in the liquid, usually 100 to 20
By passing this through the adsorption cylinder, the B content can be reduced to 1 ppb or less (the same applies hereinafter).

Next, the present invention will be explained in detail by showing examples and comparative examples.

[Example 1] Chloroform to OmjK succinonitrile, which was sufficiently dehydrated by adding anhydrous sodium sulfate in advance: 4.2! i
Dissolve and add soaked inch pellets of JE-15p (manufactured by Union Showa): 4.2.9 (approximately 10w of JE-157) to this solution.
t%) was added. This was placed in a rotary evaporator and immersed at room temperature for 2 hours, during which time it was slowly stirred by mouth. Next, the entire amount of chloroform was evaporated at 50°C under reduced pressure, and after drying, 146vrv was added to a 21uIy5 adsorption cylinder.
tL (50 cTA) was loaded.

On the other hand, BCfk5vrt% was added to SiH, C1l, diluted with H, and StH* (Jt:
1, OXl 0 mol/l, BC/3: 47
A mixed gas of X10mo and τ was prepared. This gas was transferred to the above adsorption cylinder at room temperature, and analyzed for T3C4°, etc. (3y: 18 oh"t' street, exit Cl/X). For analysis, gas chromatography and alkali solution collection ICP
(#groove-coupled high-frequency plasma) method (analysis of Sl, n) was used in combination. The values of both methods were in good agreement.

The results are shown in FIG. 2 and Table 1. In the figure, C and C0 are 5iHs C1*aB(1
, the concentration of , ■ is the volume of gas passed through, and vo is the volume of adsorbent.

As is clear from the figure, SiH! (
Although Jt is also adsorbed, it begins to flow out from around 800 bed volume C or below (denoted as B, V, V/V). After that, 12500B, B (J.

was not detected. That is, 8oo~12500B
, V is not included in Bcls'. In addition, the amount of B Ce m adsorbed up to breakthrough point 12 was B(J,·82 ri/1 fi·adsorbent).

[Example 2] BC# was added to SiH, (J, to a concentration of 12 wt%, and this was diluted with H to form SiH, (J, :tOX
l 0-” mol/J, B Cg@: 1.
Prepare a mixed gas of 2X10-% ol/J and add this to -2
The procedure was carried out in exactly the same manner as in Example 1, except that 88 L (30 cra) of 11EIIIO was filled into an adsorption cylinder.

The results are shown in Table 1.

[Example 3] An undiluted gas containing 8LH, C1l, and BCI added to 110wtPP was added to Succinonitri #10.
JE-15-p loaded with wt% was added to a 17-jaw adsorption tube.
After filling and flushing 001L, B(1) was removed in a busy manner as in Example 1. At this time, in order to prevent condensation of StH and CeR, the gas reservoir and each piping were heated to about 40°C. It was heated to ensure a stable gas flow.The results are shown in Table 1.

As is clear from Table 1, the amount of BCI3 adsorbed in Example 2. 1. This is because the higher the concentration of B(1) in the gas, the more BC(1) is adsorbed; the higher the concentration of SLH, Cl*, the more , reducing the adsorption amount of B(1, and Be
/81H,C(1m +B(Js f) The larger the B
(This is thought to be due to the adsorption capacity trend of general adsorption, such as an increase in the adsorption amount of 1).

Therefore, in order to facilitate handling, significantly shorten operating time, and facilitate analysis by gas chromatography, B(Jm/5tl-I) was diluted with an inert gas.
, CI! , +B(J), it is possible to compare the superiority of adsorbents as long as they are operated under the same conditions.

B(1,0 analysis method is triphenylchloromethane ((C
Trichloromethane (CI
(Jl) solution was brought into contact with 81 CJ*, BCe was collected as a nonvolatile component, S1, C6, CHC, etc. were dissipated and removed, the organic matter was decomposed, and B was detected by ICP method. This analysis method can analyze up to 1 ppb of B in sample 2001 with good reproducibility.

[Examples 4 and 5, Comparative Examples 1 to 3] Example 4 uses adiponitrile, Example 5
B(J〆stHcg*-83
Comparative Examples 1 and 2 used activated carbon and silica gel as carriers, Comparative Example 3 used BCg
, using triphenylchloromethane other than nitrile as a scavenger. The results are shown in Table 2.

〔effect〕

As described above, the method for purifying S LH* Cll* according to the present invention uses an adsorbent in which nitrile is supported on high-silica zeolite, which is stable and has high adsorption power for Si and I% CIl*. By simply passing 5iHIC/l containing a boron compound vaporized from a cylinder under normal temperature and pressure, the boron compound is removed to a sufficient extent for semiconductor silicon production, making the equipment and operation simple. This is an excellent method that enables efficient purification.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the method of the present invention, and FIG. 2 is a diagram showing changes over time in the components at the outlet of the adsorption column. 1...Cylinder, 2...Mass 7a-controller, 3...Nitrile-supported high silica zeolite, 4...Adsorption cylinder, 6...・・・
Cryogen, 7...Collection device, 8...Collection device,
8 &... Exit line, 9... High purity S
iH* C6,10...Inert gas, 12.
... Breakthrough point, C ... Adsorption cylinder outlet concentration, C
0...adsorption cylinder inlet concentration, ■...passing gas amount, vo...adsorbent capacity.

Claims (1)

[Claims] 1. A method for purifying dichlorosilane, which comprises bringing dichlorosilane into contact with a high silica zeolite supporting nitrile in a gas phase to remove contained boron compounds.