JP2501147B2 - Method for producing high-purity alkylphosphine - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing high-purity alkylphosphine. In particular, the present invention is a MOCVD (Met
The present invention relates to a method for producing a high-purity alkylphosphine as a raw material for forming a compound semiconductor thin film by the alorganic Chemical Vapor Deposition method.

[0002]

2. Description of the Related Art Group III-V compound semiconductor thin films such as indium-phosphorus are useful as materials for producing electronic devices. As a method of forming a compound semiconductor thin film, MBE (Molecular Beam Epitaxy), halide
CVD, MOCVD, MOMBE (Metal-organic Molecular Beam
Epitaxy). Among these, MOCVD or
MOMBE is a crystal growth method that is attracting attention as it is used more frequently because it does not need to maintain a high vacuum inside the crystal growth system, the material can be easily replaced, and maintenance is easy.

However, when a group III-phosphorus compound semiconductor is produced by these methods, since phosphine, which is a highly toxic phosphorus hydride, is used as a raw material for the phosphorus compound, a large amount of the raw material is used for mass production. I'm worried.

Therefore, in recent years, alkylphosphine has been proposed as a phosphorus raw material in place of phosphine. In particular, since monoalkylphosphine has two hydrogen atoms, it is attracting attention as a phosphine substitute material with less carbon contamination in the semiconductor thin film and reduced toxicity. [Eg J. Crystal Growth.
77 (1986) 11].

As a method for synthesizing an alkylphosphine, reduction of an alkylhalogenoline compound with lithium aluminum hydride or sodium 2RPCl ₂ + LiAlH ₄ → 2RPH ₂ + LiAlCl ₄ RPCl ₂ + 4Na (+ H ₂ O) → RPH ₂ + 2NaCl + 2NaOH dialkyl phosphonite or Reduction of dialkyl phosphonates with lithium aluminum hydride R ¹ P (OR ² ) ₂ ＋ LiAlH ₄ → R ¹ PH ₂ Reaction of phosphine with olefin PH ₃ ＋ C _n H _2n → C _n H _{2n + 1}・ PH ₂ ＋ (C _n H _{2n + 1} ) ₂・ PH ＋ (C _n H
_{2n + 1} ) ₃ P and the like are known (wherein R, R ¹ and R ² represent an alkyl group).

[0006]

Among the synthetic methods of these alkylphosphines, in the reduction method such as the method described above, lithium aluminum hydride (LiAlH ₄ ) and sodium bis (bis) hydride are mainly used as reducing agents from the viewpoint of yield. (2-Methoxyethoxy) aluminum (NaA
Although it is advantageous to use a compound having an active hydride in the molecule, such as 1H ₂ (OC ₂ H ₄ OCH ₃ ) ₂ ) or sodium borohydride (NaBH ₄ ), in such a reduction reaction, Usually, the reaction product of the reduction was hydrolyzed with an aqueous hydrochloric acid solution, and the organic phase was extracted and distilled to produce an alkylphosphine (for example, New Experimental Chemistry Course 15,
Organic metal).

However, these reducing agents contain a trace amount of silicon, and there is a problem that they are mixed in the product alkylphosphine. The silicon mixed in the alkylphosphine is difficult to remove even by precision distillation, which is an obstacle to high purification. In particular, alkylphosphine is
In the case of using as a raw material for MOCVD of a group V compound semiconductor, silicon, which is a group IV element, is an active species, and when silicon is mixed in, the characteristics of the compound semiconductor are remarkably deteriorated, and it is one of the elements that must be reduced as much as possible.

The inventors of the present invention have studied the reduction of silicon contained in a method for producing an alkylphosphine by reducing an alkylhalogenoline compound with a reducing agent, and as a result, decomposed the product after completion of the reduction reaction. Focusing on the relationship between the concentration of hydrochloric acid used for the above and the amount of silicon mixed into the alkylphosphine, the inventors have found that the silicon in the alkylphosphine can be significantly reduced by hydrolyzing with water and performing precision distillation.

Accordingly, it is an object of the present invention to provide a method for obtaining high purity alkylphosphine having reduced silicon.

[0010]

DISCLOSURE OF THE INVENTION The present invention reduces an alkylhalogenoline compound with a reducing agent having an active hydride in the molecule to synthesize an alkylphosphine, in which the reduction reaction product is hydrolyzed with water. And a method for producing an alkylphosphine, characterized in that the alkylphosphine is separated and recovered.

The present invention is directed to phosphonyl dihalides (RP
X ₂ ) or phosphonyl dihalide (RP (O) X ₂ )
Of monoalkylphosphines by reduction of alkyldihalogenoline compounds such as, phosphinyl halides (R ₂ PX) or phosphinyl halides (R ₂ P
It can be applied to any of the production of dialkylphosphines by reduction of dialkylhalogenoline compounds such as (O) X).

Further, the present invention can be applied to the production of alkylphosphine having any alkyl group,
In particular, it can be applied to the production of monoalkylphosphine such as isopropyl, tert-butyl, phenyl, etc., which is a raw material when forming a compound semiconductor thin film by the MOCVD method, to produce a monoalkylphosphine containing few impurities.

The reducing agent used in the present invention is a compound having an active hydride in the molecule, such as lithium aluminum hydride (LiAlH ₄ ), sodium bis (2-methoxyethoxy) aluminum hydride (NaAlH ₂ (OC ₂ H _2
4 OCH ₃ ) ₂ ) or sodium borohydride (N
aBH ₄ ), etc., but sodium bis (2-methoxyethoxy) aluminum hydride is superior in that it contains less alkyl halide in the product.

The water used for the hydrolysis is neutral water such as pure water, and preferably has a pH of 6 to 8, particularly 6.5 to 7.5.

From the viewpoint of yield, it is preferable that the amount of water used for hydrolysis is more than the amount at which the yield is saturated. However, if the amount of water increases, the reaction vessel becomes larger, so it is advisable to carry out with the amount of water suitable for the reaction system.

Since a large amount of gas is generated in the initial stage of hydrolysis, it is necessary to control the dropping rate so that a runaway reaction does not occur.

[0017]

EXAMPLES All operations were carried out under an inert atmosphere. Example 1 347 g of 70% sodium bis (2-methoxyethoxy) aluminum hydride toluene solution was placed in a flask,
Toluene was distilled off under reduced pressure by heating at 100 ° C., 5 mmHg for 3 hours. After returning to room temperature, 200 ml of dibutyl ether
70 g of tert-butyldichlorophosphonyl (tert-BuP (O) Cl ₂ ) which had been added and dissolved was placed in a dropping funnel and added dropwise to bis (2-methoxyethoxy) aluminum hydride cooled to about -10 ° C. .
After completion of dropping, the mixture was heated and stirred at about 60 ° C. for 1 hour. After returning to room temperature, it was cooled to about -10 ° C again, and 900 ml of water was gradually added. The reaction solution became cloudy and when it was further added, it was completely separated into two phases. The upper organic phase was extracted and distilled to obtain 18 g of colorless liquid (yield 50%). The silicon content determined by ICP was 0.2 ppm. This is 30 cm in length
When rectification was performed twice using a distillation column filled with Raschig rings, the silicon content was 0.03 ppm or less, which is the lower limit of quantification of ICP.

Using the obtained tert-butylphosphine and commercially available trimethylindium, a horizontal MO
In using a CVD apparatus at a growth temperature of 600 ° C. and a V / III ratio of 30
An InP epitaxial film is grown under atmospheric pressure on a P substrate, and V
The results of measuring the electrical characteristics by the and der Pauw method are as follows. Mobility μ _77k = 50500 cm ² / v · sec Carrier concentration η _77k = 1.7 × 10 ¹⁵ cm ⁻³ .

Comparative Example 1 Sodium bis (2-methoxyethoxy) aluminum hydride 70% toluene solution 357 g and tert-butyldichlorophosphonyl (t-BuP (O) Cl ₂ ) 72 g
Was reacted in the same manner as in Example 1, and after the reaction, hydrolysis was performed with 900 ml of a 6N hydrochloric acid aqueous solution instead of water.
The organic phase was subjected to extractive distillation to obtain 21 g of a colorless liquid (yield 56
%). The silicon content was determined by ICP to be 0.
It was 7 ppm. This was rectified twice using a distillation column filled with a Raschig ring having a length of 30 cm, and the silicon content in the product was 0.8 ppm even after the rectification.

MOC was obtained from the obtained tert-butylphosphine and commercially available trimethylindium in the same manner as in Example 1.
An InP epitaxial film was prepared by a VD apparatus and the electrical characteristics were measured. As a result, the mobility was μ _77k = 7900 cm ² / v · sec, the carrier concentration was η _77k = 2.3 × 10 ¹⁶ cm ⁻³ , and it was hydrolyzed with water. As a result, the one having sufficient electric characteristics was not obtained as compared with the one obtained.

[0021]

EFFECTS OF THE INVENTION According to the present invention, the reduction reaction product of an alkylhalogenoline compound with a reducing agent having an active hydride in the molecule is hydrolyzed with water to obtain a silicon compound having a high purity of less than the lower limit of wet analysis quantitative determination. An alkylphosphine can be obtained and can be used as a raw material for a high-performance Group III-V compound semiconductor thin film.

Claims (1)

(57) [Claims] 1. In a reaction for synthesizing an alkylphosphine by reducing an alkylhalogenoline compound with a reducing agent having an active hydride in the molecule, the reduction reaction product is hydrolyzed with water to separate and recover the alkylphosphine. A method for producing an alkylphosphine, comprising: