JP5489155B2 - Method for purifying trialkylaluminum - Google Patents

Description

  The present invention relates to trialkylaluminum. In particular, the present invention relates to a trialkylaluminum used for forming an Al-based film such as an Al-based film for compound semiconductors.

  Compound semiconductors are useful in the fields of semiconductor light emitting diodes, lasers, infrared detectors, and the like. And the quality of the compound semiconductor obtained by carrying out vapor phase growth of an organometallic compound is greatly influenced by the impurity of the organometallic compound which is a raw material.

  For example, oxygen (O) in trialkylaluminum (for example, trimethylaluminum), which is one of raw materials for vapor deposition of compound semiconductors, is still one of the major problems that cannot be solved.

That is, trimethylaluminum reacts sensitively with oxygen and moisture, causing ignition and smoke generation. For this reason, oxygen impurities in trialkylaluminum are not limited to oxygen and moisture, but include (having) a compound containing (having) oxygen (O), such as aluminum alkoxide [(CH ₃ ) ₂ Al—O—CH ₃ ]. Forms are also included.

Now, if oxygen molecules (O ₂ ) are mixed, such impurities can be easily removed by, for example, a distillation operation. Alternatively, it can be easily removed by a deaeration operation. If mixed with water (H ₂ O), it can be easily removed by a dehydration operation with a desiccant, for example.

However, oxygen atoms (O) mixed in a form such as aluminum alkoxide [(CH ₃ ) ₂ Al—O—CH ₃ ] cannot be easily removed. In particular, in the case of trimethylaluminum, the mixed oxygen-containing compound is difficult to separate even by precision distillation due to its azeotropic phenomenon.

  Therefore, a method of removing the oxygen compound by reaction with a reducing agent can be considered.

  As the reducing agent in the above method, alkali metal reducing agents such as Li and Na are known. However, alkali metals cause defects in semiconductor devices. Therefore, the use of alkali metals should be avoided.

  Alkaline earth metals are also known as reducing agents. Alkaline earth metal reducing agents also have a strong reducing ability. For example, dimethylmagnesium has a very low vapor pressure, so that it can be easily separated by distillation after the reaction. However, dimethylmagnesium forms a complex with trialkylaluminum. For this reason, when dimethylmagnesium is used for the production (purification) of trialkylaluminum, it cannot be separated by distillation.

  Other groups also show reducing properties. However, since it has a high vapor pressure, separation is difficult even if a distillation operation is performed after the reduction reaction.

Therefore, the problem to be solved by the present invention is to provide high purity trialkylaluminum.
For example, it is to provide a technique capable of removing oxygen-containing compounds (impurities) in trialkylaluminum. Furthermore, it is to provide a technique capable of easily separating a compound used as a reducing agent and trialkylaluminum after removing an oxygen-containing compound (impurities) by a reduction reaction.

  While research for solving the above-mentioned problems has been earnestly advanced, the present inventor has found that the oxygen concentration in the trialkylaluminum is lowered by biscyclopentadienylmagnesium. Furthermore, it was found that biscyclopentadienyl magnesium does not form a complex with trialkylaluminum, and it was also found that separation from biscyclopentadienyl magnesium is possible by distillation.

  The present invention has been achieved based on such findings.

That is, the above problem is
This is solved by a method for producing trialkylaluminum, which comprises contacting oxygen-containing trialkylaluminum with bisalkylcyclopentadienylmagnesium.

  For example, this can be solved by a method for producing trialkylaluminum, which comprises mixing trialkylaluminum having oxygen and bisalkylcyclopentadienylmagnesium.

  Alternatively, the problem is solved by a method for producing trialkylaluminum, which comprises refluxing trialkylaluminum having oxygen and bisalkylcyclopentadienylmagnesium.

  Alternatively, the problem is solved by a method for producing trialkylaluminum, characterized in that trialkylaluminum having oxygen is passed through bisalkylcyclopentadienylmagnesium.

  Alternatively, the problem can be solved by a method for producing trialkylaluminum, characterized by passing trialkylaluminum in the gas phase containing oxygen through bisalkylcyclopentadienylmagnesium.

  The trialkylaluminum production method described above is preferably solved by a trialkylaluminum production method comprising a distillation step after the contact step between the trialkylaluminum and the bisalkylcyclopentadienylmagnesium. The

  The trialkylaluminum production method described above is preferably solved by a trialkylaluminum production method comprising a filtration step after the contact step between the trialkylaluminum and the bisalkylcyclopentadienylmagnesium. The

  Moreover, it solves with the trialkylaluminum obtained by the manufacturing method of the said trialkylaluminum.

  High-purity trialkylaluminum with few impurity components having O can be easily obtained.

Schematic diagram of trialkylaluminum production equipment (purification equipment) Schematic diagram of trialkylaluminum production equipment (purification equipment) Schematic diagram of trialkylaluminum production equipment (purification equipment)

  The present invention is a production method (purification method) of trialkylaluminum. This method includes a step of contacting trialkylaluminum having oxygen (for example, trialkylaluminum having O as an impurity component) with bisalkylcyclopentadienylmagnesium. For example, there is a step of treating trialkylaluminum having oxygen and bisalkylcyclopentadienylmagnesium. For example, the method includes a process of mixing trialkylaluminum having oxygen and bisalkylcyclopentadienylmagnesium. Alternatively, the method includes a step of refluxing trialkylaluminum having oxygen and bisalkylcyclopentadienylmagnesium. Alternatively, the method includes a step of passing a trialkylaluminum having oxygen through bisalkylcyclopentadienylmagnesium. Alternatively, a step of passing a trialkylaluminum in a gas phase state (or a liquid phase state) having oxygen through bisalkylcyclopentadienylmagnesium is provided. Preferably, after the contact step, a distillation step and / or a filtration step are included.

Trialkylaluminum is a compound represented by R ₃ Al or RR′R ″ Al (R, R ′, R ″ are alkyl groups, and R, R ′, R ″ may be the same or different). , (CH ₃ ) ₃ Al, (C ₂ H ₅ ) ₃ Al, (C ₃ H ₇ ) ₃ Al, (C ₄ H ₉ ) ₃ Al, (CH ₃ ) ₂ AlC ₂ H ₅ , (C ₂ H ₅ ) _{2 A} typical example is a trialkylaluminum such as AlCH _{3. A} preferable alkyl group is a hydrocarbon group having 7 or less carbon atoms, and a more preferable alkyl group is a hydrocarbon group having 4 or less carbon atoms. The alkyl groups may be all the same or different, and the oxygen-containing trialkylaluminum (R ₃ Al, RR′R ″ Al) means that R, R ′, R ″ are RO, R Alkoxy like 'O, R "O Compounds of structure behalf group can be cited as typical examples. For example, a compound represented by RR'AlOR "or the like.

Bisalkylcyclopentadienyl magnesium is, for example, a compound represented by the following general formula [I].
Formula [I]
In the general formula [I], R _{1 to} R ₁₀ are H or an alkyl group. A preferred alkyl group is a hydrocarbon group having 7 or less carbon atoms. More preferred alkyl groups are hydrocarbon groups having 4 or less carbon atoms.

  Particularly preferred bisalkylcyclopentadienyl magnesiums include biscyclopentadienyl magnesium, bismethylcyclopentadienyl magnesium, bisethylcyclopentadienyl magnesium, bisisopropylcyclopentadienyl magnesium, and bistally butylcyclopentadienyl. Examples include magnesium and bispentamethylcyclopentadienyl magnesium.

  Hereinafter, the present invention will be described with specific examples. However, the present invention is not limited to this embodiment.

[Example 1]
Trimethylaluminum [TMAl: (CH ₃ ) ₃ Al] was purified using biscyclopentadienylmagnesium [Cp ₂ Mg].

  That is, the apparatus shown in FIG. 1 was used. In FIG. 1, 1 is a distillation kettle, 2 is a distillation column, 3 is a tower top thermometer, 4 is a cooler, and 5 is an effluent collector.

First, 2 g of Cp ₂ Mg was placed in the still 1. Thereafter, 50 g of TMAl (TMAl has O as an impurity component) was added.

  Thereafter, a reflux treatment was performed. After 2 hours, TMAl distilled at a distillation column top temperature of 125 ° C. was collected in the collector 5.

  When the solution remaining in the still 1 after the reflux / distillation treatment was observed, it was colored light red.

The thing refine | purified by the said reflux and distillation process was analyzed by H-NMR. As a result, the peak intensity due to the protons of CH ₃ O—Al was reduced to 1/5 or less as compared with that before treatment. And a peak derived from _Cp 2 Mg was observed.

[Example 2]
In Example 1, it was carried out in the same manner except for using MeCp ₂ Mg instead of _Cp 2 Mg (bis-cyclopentadienyl magnesium).
The result was similar. That is, the peak intensity due to the protons of CH ₃ O—Al was reduced to 1/5 or less as compared with that before the treatment. And, a peak derived from MeCp ₂ Mg was observed.

[Example 3]
In Example 1, it was carried out in the same manner except for using instead EtCp ₂ Mg of _Cp 2 Mg (bis-ethyl-cyclopentadienyl magnesium).
The result was similar. That is, the peak intensity due to the protons of CH ₃ O—Al was reduced to 1/5 or less as compared with that before the treatment. And, a peak derived from EtCp ₂ Mg was observed.

[Example 4]
In Example 1, it was carried out in the same manner except for using i-PrCp ₂ Mg (bis-isopropylcyclopentadienyl magnesium) instead of _Cp 2 Mg.
The result was similar. That is, the peak intensity due to the protons of CH ₃ O—Al was reduced to 1/5 or less as compared with that before the treatment. And a peak derived from the i-PrCp ₂ Mg was observed.

[Example 5]
In Example 1, were carried out in the same manner except for using, instead of _{Cp 2 Mg t-BuCp 2 Mg} ( Bicester tertiary butyl cyclopentadienyl magnesium).
The result was similar. That is, the peak intensity due to the protons of CH ₃ O—Al was reduced to 1/5 or less as compared with that before the treatment. In addition, no peak derived from t-BuCp ₂ Mg was observed.

[Example 6]
In Example 1, it was carried out in the same manner except for using _Me 5 _Cp 2 Mg (bis-pentamethylcyclopentadienyl magnesium) instead of _Cp 2 Mg.
The result was similar. That is, the peak intensity due to the protons of CH ₃ O—Al was reduced to ¼ or less as compared with that before treatment. And _a peak derived from Me 5 _Cp 2 Mg was observed.

[Example 7]
In Example 1, it carried out similarly except having used TEAl (triethylaluminum) instead of TMAl.
The result was similar. That is, the peak intensity due to the protons of C ₂ H ₅ O—Al was reduced to ¼ or less compared to that before treatment. And a peak derived from _Cp 2 Mg was observed.

[Example 8]
In Example 1, it carried out similarly except having used TPAl (tripropylaluminum) instead of TMAl.
The result was similar. That is, the peak intensity due to the protons of C ₃ H ₇ O—Al was reduced to ¼ or less compared to that before treatment. And a peak derived from _Cp 2 Mg was observed.

[Example 9]
In Example 1, it carried out similarly except having used TBAl (tributylaluminum) instead of TMAl.
The result was similar. That is, the peak intensity due to the protons of C ₄ H ₉ O—Al was reduced to ¼ or less as compared with that before the treatment. And a peak derived from _Cp 2 Mg was observed.

[Example 10]
In Example 1, it carried out similarly except having used DMEAl (dimethyl ethyl aluminum) instead of TMAl. The result was similar.

[Example 11]
The apparatus shown in FIG. 2 was used. In FIG. 2, 1 is a container containing TMAl (TMAl has O as an impurity component), 2 is a container containing Cp ₂ Mg, 3 is a collector, 4 is a cooler, and 5 is piping. , 6 are nitrogen gas cylinders.
Container 2 contains 30 g of Cp ₂ Mg. Then, nitrogen gas was supplied into the container 1 from the nitrogen gas cylinder 6. By bubbling with the supplied nitrogen gas, TMAl in the container 1 was sent into the container 2 in a gas phase state.
This sent TMAl passed through the container 2 while contacting with Cp ₂ Mg. TMAl exiting the container 2 was cooled by the cooler 4 and collected in the container 3.
TMAl purified with Cp ₂ Mg by the above method was analyzed by H-NMR. As a result, the peak intensity due to the protons of CH ₃ O—Al decreased to 1/3 or less as compared with the product before treatment (purification). And a peak derived from _Cp 2 Mg was observed.

[Example 12]
The apparatus shown in FIG. 3 was used. In FIG. 3, 1 is a container containing TMAl (TMAl has O as an impurity component), 2 is a Cp ₂ Mg filled container, 3 is a collector, 4 is a filter, 5 is piping, 6 is Nitrogen gas cylinder.
Container 2 contains 30 g of Cp ₂ Mg. Then, nitrogen gas was supplied into the container 1 from the nitrogen gas cylinder 6. TMAl (liquid) in the container 1 was pumped into the Cp ₂ Mg filled container 1 by bubbling with the supplied nitrogen gas.
The pumped liquid TMAl, while in contact with _Cp 2 Mg, passed through the _Cp 2 Mg layer. Then, the liquid TMAl exiting the Cp ₂ Mg filled container 2 was filtered by the filter 4 and collected in the container 3.
TMAl purified with Cp ₂ Mg by the above method was analyzed by H-NMR. As a result, the peak intensity due to the protons of CH ₃ O—Al was reduced to ¼ or less compared to the product before treatment (purification). And a peak derived from _Cp 2 Mg was observed.

[Comparative Example 1]
In Example 1, it was carried out in the same manner except for using _Me 2 Mg (dimethyl magnesium) instead of _Cp 2 Mg.
In the case of this comparative example, a complex [Me ₈ Al ₂ Mg] was observed in the distilled liquid.

Claims (8)

R ¹ R ² R ³ Al ( at least one of R ¹ , R ² , R ³ is an alkoxide group, and the remaining groups when not all are alkoxide groups are alkyl groups), and R ⁴ R ⁵ R A method for purifying R ⁴ R ⁵ R ⁶ Al from a substance containing ⁶ Al (R ⁴ , R ⁵ , and R ⁶ are alkyl groups) ,
Wherein R ^{1 R} 2 ^R 3 ^Al and purification method of trialkylaluminum, wherein <br/> by comprising the step of contacting the bis-alkyl cyclopentadienyl magnesium. The contact process is
R ¹ R ² R ³ Al and ^R 4 ^R 5 ^R a substance containing 6 Al, and a bis-alkyl cyclopentadienyl magnesium, bird according to claim 1, characterized in that the step of mixing process <br/> A method for purifying alkylaluminum. The contact process is
A material containing R ¹ R ² R ³ Al and ^R 4 ^R 5 ^R 6 Al, and a bis-alkyl cyclopentadienyl magnesium, bird according to claim 1, characterized in <br/> be a step of refluxing A method for purifying alkylaluminum. The contact process is
The substance containing the R ¹ R ² R ³ Al and ^R 4 ^R 5 ^R 6 Al, through the bisalkyl cyclopentadienyl magnesium, trialkyl claim 1, characterized in <br/> be a step of passing A method for purifying aluminum. The contact process is
Claims a material of gas phase containing R ¹ R ² R ³ Al and ^R 4 ^R 5 ^R 6 Al, through the bisalkyl cyclopentadienyl magnesium, and wherein the <br/> be a step of passing 1. A method for purifying trialkylaluminum. 6. The method for purifying trialkylaluminum according to claim 1, further comprising a distillation step after the contacting step. The method for purifying trialkylaluminum according to any one of claims 1 to 6, further comprising a filtration step after the contacting step. Bisalkylcyclopentadienyl magnesium is
Biscyclopentadienylmagnesium, bismethylcyclopentadienylmagnesium, bisethylcyclopentadienylmagnesium, bisisopropylcyclopentadienylmagnesium, bistally butylcyclopentadienylmagnesium, bispentamethylcyclopentadienylmagnesium The method for purifying trialkylaluminum according to any one of claims 1 to 7, wherein the compound is one or more compounds selected from the group consisting of: