JPH02295991A - Preparation of gallium alkyl compound - Google Patents

Abstract

PURPOSE: To obtain a high purity compound useful for the production of semiconductors inexpensively and simply by reacting a gallium halogenide with an alkyl aluminum halogenide in the presence of a metal halogenide.

CONSTITUTION: A gallium halogenide (example: an alkyl gallium dihalogenide etc.), is reacted with an alkyl aluminium halogenide (example: a dialkyl aluminum halogenide, etc.), in the presence of a metal halogenide as an auxiliary base (example: sodium chloride, etc.), at a temperature which causes the pyrolysis of the reaction product (70-450°C) in the liquid area of the reaction mixture to obtain the objective compound. Pollutants existing in the final product are removed in the final purification by additing sodium fluoride.

COPYRIGHT: (C)1990,JPO

Description

[Detailed description of the invention] [Industrial application field] The present invention provides a method according to claim 1 for producing gallium-1-2-2- The present invention relates to a method for producing an alkyl compound.

[Prior Art] Gallium alkyl compounds, especially those with small alkyl groups, are used in III/V semiconductors, especially III/V semiconductors from gallium arsenide and gallium phosphide, which are used in the electrical and solar industries. is important during the production of products (of which demand is increasing). Significant difficulties have heretofore been encountered in producing this gallium alkyl compound in the required purity and quantity.

Gallium halogen compounds can be alkylated with Grignard reaction reagents, but a significant drawback is that the ethers that are most commonly used as solvents form stable addition products with the resulting gallium trialkyl. Separation of this addition product is extremely difficult and usually involves partial thermal decomposition of the desired gallium alkyl and corresponding impurity. Similar problems arise with a variant of the Grignard reaction, namely the reaction of (possibly metal-doped) magnesium-gallium alloys with alkyl halides. Alkyl lithium or alkyl sodium
Alkylation with compounds can also be carried out in the case of small alkyl groups only in the presence of a concomitant solvent, which has this disadvantage.

The use of a liquid metal alkyl avoids the difficulties of subsequent solvent removal, but only by the use of a stoichiometric excess of this alkylating agent during the reaction of the gallium halide with the trialkylaluminium. , high yields can be obtained using only one of the three alkyl groups. Although the reaction of dialkylmercury for the transfer of alkyl groups onto gallium is itself very slow even under HgCl2-catalysis, the marked toxicity of dialkylmercury compounds is
Prohibits wide use. Finally, the dialkyltin compounds that can be used for the alkylation of gallium halides are:
Difficult to obtain as a starting material.

The well-known Wurtz synthesis of the simultaneous reaction of alkyl halides and metal halides in the presence of sodium
-5ynthese), each two alkyl groups react to form a higher hydrocarbon, which not only leads to impurity, but also particularly in the production of gallium alkyl compounds, since the gallium halide used is reduced to gallium metal. It is particularly unsuitable for this purpose. The same applies to halogen-accepting metals other than sodium, such as metals of groups I to III of the periodic table (
These also apply to the Wurz-like reaction, which has already been detected in organic solvents and in salt melts as solvent.

Moreover, the latter remains limited to the methylation of low positive elements, based on side reactions of higher alkyl halides. The corresponding state of the art is the West German patent (DE-P)
S) No. 1239689, East German Patent (Do-ps)
No. 231568 and British Patent (GB-O5) No. 212
It is described in the specification of No. 3423.

[Problem to be Solved by the Invention] The problem to be solved by the present invention is to solve the problem of using CVD-based gallium alkyl compounds, which are important for modern semiconductor manufacturing, especially due to their easy volatility.
An object of the present invention is to produce a short-chain gallium alkyl compound, which is advantageous in a process, in a large quantity and with high purity by a simple method from inexpensive and easily available precursors.

Means for Solving Problem E] This problem is solved by the present invention, starting from the state of the art considered in the generic concept of claim 1, and using the features described in the characterizing part of claim 1. be done.

Advantageous aspects of the invention are set out in claims 2 to 11.

As already mentioned, hard-to-obtain aluminum trialkyls react with gallium halides with transfer of only one of the three alkyl groups. The dialkylaluminum halogenides which form as by-products exhibit no further alkylating effect on the gallium-halogen bond, which was still quite weakly expected for alkylaluminum halides. Surprisingly, the aforementioned auxiliary base (Hilfsb
It has been found that, for example, when adding alkali metal and alkaline earth metal halides to alkylaluminum dichlorides, the alkyl groups can be quantitatively transferred onto the gallium in exchange for halogen atoms. Furthermore, rather, dialkylaluminum halogenides and aluminum trialkyls and mixtures thereof may also be used in combination with alkylaluminum dichlorides, such as the commercially available so-called alkylaluminum sesquichloride R3A.
12C13) under the same reaction conditions, optionally with the addition of aluminum rogendo for the purpose of conversion and concomitant reduction of the vapor pressure of this compound. It is advantageous to operate at a temperature at which the mixture of components is in liquid form.

For example, the use of alkylaluminum sesquichloride
Along with its industrial availability, this representative with small alkyl groups is liquid without too extreme deviations from the usual conditions, and therefore its handling, dosing, stirring, etc. in the process of the invention is very simple. This has the particular advantage of being pyrophoric, which is important due to the autoignition properties of the reaction components.

Of the auxiliary bases, chloride is the cheapest due to its industrial availability, and this also applies to the exchange reagent aluminum chloride, so the process of the invention operates with chloride or mixtures thereof. It is advantageous to do so. The simple addition of the auxiliary base sodium chloride to the components dialkyl aluminum chloride or alkyl aluminum dichloride or mixtures thereof and gallium trichloride affects high yields of trialkyl gallium or dialkyl gallium chloride.

Additional incorporation of potassium chloride as an auxiliary base results in
As long as the given reaction temperature is well within the liquid range of the reaction mixture, the yield is further increased.Further particular advantages of the process of the invention compared to previously known processes are: Completely solvent-free Since it is operated with 100 ml, there are no separation problems or contamination. It is also clear that the space-time yield relative to the amount of total reaction components is extremely high.

The synthesis products can be drawn off in vapor form simultaneously with the pre-separation, and the by-product mixture can be discharged from the reactor in liquid form.
The aluminum can then optionally be recovered again for the production of alkyl aluminum diloride using recycling processes according to the state of the art. The gallium used for the preparation of the gallium trichloride to be used, since upon proper dosing of the auxiliary base all undesired incidental metals are present with the reaction products and therefore further purification is then carried out. It is a particular advantage that it may be of low purity (the main contaminant from the manufacturing process is aluminum).

Furthermore, the valuable product gallium (gallium compounds are still contained in the by-product mixture after this reaction, since it is not a completely quantitative reaction) is converted into aluminum metal (powder,
easily precipitated by the simple addition of debris (chips, rods, granules);
It can be recovered. Finally, in case of equipment damage, the reaction mixture is removed in liquid form and converted by cooling to room temperature into a solid agglomerate, which can be disposed of more harmlessly than is possible during synthesis in organic solvents.

The specific and important contaminants of the final product are:
(alkyl)-aluminum-halogen compounds, which, as is known, can be purified by rectification during the essential final purification of gallium trialkyl, which is important for semiconductor manufacturing, by the addition of sodium fluoride. Can be removed.

[Example] The following examples illustrate the method of the invention.

Example 1 Me3Al2C12250g, AlCl31349, N
A mixture of 1128 g aC and 67 g KCl is gradually warmed under inert gas until complete liquefaction, avoiding temperature spikes and overheating. At 110-120℃, G
Add 3176 g of aCl and heat to 350° C. for 0.5-2 hours while stirring. At this time, Me3Ga
49g (42,7%) and Me2GaC1759 (5
5.5%) is distilled out. The gallium conversion rate is 98.2%.

Example 2 Me3Al2 (j13205 g, AlCl31349
, NNaC11289KG167 is heated until completely liquefied. Me2G at 110-120℃
Add aC14069 and heat further to 350°C while stirring. At this time, Me3 with a gallium conversion rate of 97.5%
Gal 669 (48,2%) and Me2GaC12
00 g (49,3%) is obtained.

Example 3 Me3Al2C132059, AlCl31349, N
A mixture of aC11289 and 67 g of KCl is heated until completely liquefied. Ms2Ga at 110-120℃
Add 1202 g of C and heat to 200°C. Already at this temperature, at which part of the product migrates, GaCl3
Add 176 g and finally heat further to 350°C.

In total, with quantitative gallium conversion, Me3Ga 11
49 and 1201 g of Me2GaC are obtained.

Example 4 CaCl3240 g and Me3Al3C132809
14 g of NaCl and 62 g of KCl to the mixture from
and heat the mixture to 350°C. At this time, Me3Ga409 and Me2 with a gallium conversion rate of 96.1%
1130 g (70.5%) of GaC are obtained.

Example 5 Et3Al3C132479, AlCl3 134 g
and 224 g of KCl are heated until completely liquefied. At 185-195°C, add GaCl31769 and heat to 350°C. At this time, 15.8 g (10.0 g) of Et3Ga was used at a gallium conversion rate of 79.2%.

1%) and 1113 g (69.1%) of Et2GaC are obtained.

Example 6 EL3Al2C131219, AlCl3659 and K
Heat the mixture from Cl1099 until completely liquefied. At 185-195°C, add 1239 g of Et2GaC and heat to 350°C. At this time, the gallium conversion rate was 97.3%, and Et3Ga l l Og (47.9%
) and Et2GaC11189 (49.4%) are obtained.

Example 7 Et3Al l I 49 , AlCl3 1339
and 149 g of KCl in a mixture of 3176 g of CaCl.
and heat the mixture to 350°C. On this occasion,
With a gallium conversion rate of 93%, 33g of Et3Ga (21%
) and 1118 g (72%) of Et2GaC are obtained.

Claims (1)

[Claims] 1. A process for producing a gallium alkyl compound, characterized in that a gallium halide compound is reacted with an alkyl aluminum halide in the presence of a metal halide as an auxiliary base to produce the gallium alkyl compound. . 2. The method according to claim 1, wherein gallium trihalide, alkylgallium dihalide, or dialkylgallium halide is used as the gallium halide compound. 3. As the alkyl aluminum halide, dialkyl aluminum halide, alkyl aluminum dihalogenide, alkyl aluminum and dialkyl aluminum halide, or so-called sesquihalogenide (R_
2. The method as claimed in claim 1, wherein a mixture of 3Al_2X_3) is used. 4. The process as claimed in claim 3, wherein instead of the alkyl aluminum halide, a trialkyl aluminum is used with the addition of an aluminum halide. 5. The method according to claim 1, wherein a halide of a metal from groups I to III of the periodic table is used as the auxiliary base. 6. The method according to claim 1, wherein sodium chloride and/or potassium chloride are used as auxiliary bases. 7. The process according to any one of claims 1 to 6, wherein the reaction is carried out at a temperature of 70 to 450<0>C. 8. Process according to claim 1, characterized in that the reaction is carried out in the liquid region of the reaction mixture at a temperature up to which significant thermal decomposition of the reaction mixture and/or product occurs.