JPH06145177A - Purification of organometallic compound - Google Patents

Abstract

PURPOSE:To improve the purity of an organometallic compound useful as a raw material in the organometal gas phase growth method used in production of a compound semiconductor, etc. CONSTITUTION:This method for purifying an organometallic compound is characteristically carried out by heating the organometallic compound, removing low- boiling impurities using an inert carrier gas, analyzing the impurities in the carrier gas with time and monitoring the state of purification thereby. This method enables even an unexperienced man to efficiently remove the low-boiling impurities in the organometallic compound.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for purifying an organometallic compound. More specifically, the present invention relates to a method for removing low boiling point impurities in an organometallic compound for producing a compound semiconductor by a metalorganic vapor phase epitaxy method.

[0002]

2. Description of the Related Art In recent years, in the production of compound semiconductor transistors and the like, a vapor phase growth method (M
The OCVD method) has been adopted. The organometallic compound as the raw material is required to have a high purity with few impurities.

As a conventional refining method, Zhurnal Prikladnoi Khimii, 48 (8),
1810 (1975) for precision distillation of trimethylgallium and Journal of Crystal Growth, 77, 19 (19
As described in 86), there is a method in which trimethylindium and diphosphine are reacted to form an adduct, and low boiling point impurities having a high vapor pressure are removed by distillation.

[0004]

As described above, the conventional purification method is based on distillation, but the separation of a very small amount of impurities cannot be controlled at the top temperature of the distillation column. For this reason, the conditions for extracting Hatsudome were empirical.

[0005]

As a result of various investigations in view of the above, the present invention has developed a method for purifying an organometallic compound more efficiently, and is capable of inactivating low boiling impurities in an organometallic compound. It is characterized in that the purification condition is monitored by removing the impurities in the carrier gas and measuring impurities in the carrier gas with time.

The present invention will be described in more detail below. The organometallic compound of the present invention may be used as it is, or may be added to another reactant to form an adduct. The treatment temperature is not particularly limited, but it is desirable to heat at a temperature lower than the boiling point of the organometallic compound or its adduct to be purified, since only low boiling point impurities are removed. Then, the low boiling point impurities vaporized by heating are removed to the outside of the system by an inert carrier gas.

An example of an apparatus for carrying out such a purification method of the present invention is shown in FIG. That is, the organometallic compound to be purified is placed in a container such as a four-necked flask (2), the flask (2) is heated by a mantle heater or the like (4), and the inside of the flask (2) is stirred by a stirrer (3). A carrier gas such as nitrogen gas having a flow rate adjusted by the flow meter (1) is introduced into the flask (2) while being stirred.

On the other hand, the outlet pipe of the carrier gas from the flask (2) is heated by a tape heater (7) and a nitric acid trap (5) is provided on the way to collect low boiling point organometallic impurities in the carrier gas. To do. Further, the carrier gas that has passed through the trap (5) is introduced into the FID detector (6) of the gas chromatogram, and the purification status is monitored by detecting organic impurities with the detector (6).

A feature of the present invention is that a nonequilibrium state can be always created by using a carrier gas, and vaporized low boiling point impurities can be continuously removed. further,
To measure the removed impurities, the carrier gas is used as it is as a measuring device, for example, an induction plasma emission spectrometer (I
CP) or an atomic absorption spectrophotometer, or the like, or once collected in an acid or a cold trap and then prepared as a sample for measurement by various analyzers. The removal of impurities can be interrupted at any time by stopping the carrier gas, and restarted immediately after flowing the carrier gas.

After confirming that the low-boiling-point impurities have been eliminated in this way, a normal distillation operation can be carried out to ensure the purification.

The organometallic compounds of aluminum, gallium and indium which are the subject of the present invention are represented by the general formula R _a MX
_3-a (wherein R is an alkyl group having 1 to 4 carbon atoms, M is aluminum, gallium or indium, X is halogen,
a represents an integer of 2 or 3. ) Is a compound or an adduct thereof.

Specifically, trialkyl such as trimethyl aluminum, triethyl aluminum, tripropyl aluminum, tributyl aluminum, trimethyl gallium, triethyl gallium, tripropyl gallium, tributyl gallium, trimethyl indium, triethyl indium, tripropyl indium, tributyl indium, etc. Metal compounds, alkyl halide metal compounds such as dimethyl aluminum chloride, diethyl aluminum chloride, dimethyl gallium chloride, diethyl gallium chloride, dimethyl indium chloride, diethyl indium chloride, trimethyl aluminum / dyphosphine adducts, trimethyl gallium /
Examples include adducts of alkyl metal compounds such as diphosphine adducts and trimethylindium / dyphosphine adducts.

[0013]

EXAMPLES The present invention will be described below with reference to examples using the apparatus of FIG.

(Example 1) 4 made of glass with an internal volume of 300 ml
After replacing the neck flask with nitrogen gas, n-heptadecane 200
ml and crude trimethylindium 80 g were charged. The crude trimethylindium contained aluminum component 2000 ppm, silicon component 6 ppm, toluene 600 ppm, and heptane 1200 ppm.

This container was attached to a purifier as shown in FIG. 1 and heated to 140 ° C. Nitrogen gas was flowed at 200 ml / min as a carrier gas. A trap containing 50 ml of 1N nitric acid was attached to the carrier gas outlet to collect low-boiling organometallic impurities in the carrier gas. The trap was replaced every 2 hours and the collected metal impurities were analyzed by ICP. Further, the carrier gas passing through the trap was introduced into the FID detector of the gas chromatograph to detect organic impurities. Organic impurities were no longer detected after 4 hours. Aluminum and silicon were not detected after 18 hours and 8 hours, respectively.

After all impurities were not detected, trimethylindium was heated to 140 ° C. at 50 torr and distilled out from n-heptadecane. Impurities in the obtained trimethylindium were 0.2ppm in the aluminum component.
Below, the silicon content was 0.3 ppm or less, and both toluene and heptane were 1 ppm or less.

(Example 2) Using the same apparatus as in Example 1, 80 g of crude triethylindium and n-heptadecane 2
00 ml was charged into a 300 ml four-necked flask, heated to 130 ° C., and nitrogen gas was flowed at 200 ml / min as a carrier gas.
The crude triethylindium contained 1300 ppm of aluminum component, 50 ppm of toluene, and 700 ppm of high purity for hepta child material.

Organic impurities were no longer detected after 4 hours. Aluminum disappeared after 20 hours.

After all impurities are no longer detected,
Heat triethylindium to 105 ° C at 5 torr and
-Distilled off from the heptadecane. Regarding the impurities in the obtained triethylindium, the aluminum component was 0.2 ppm or less, and both toluene and heptane were 1 ppm or less.

Example 3 In the same manner as in Example 1, 80 g of an adduct of trimethylaluminum diphosphine,
200 ml of n-heptadecane was charged into a 300 ml four-necked flask and heated at 110 ° C, and nitrogen gas as a carrier gas was added.
Flowed at 00 ml / min. Impurities in the adduct of trimethylaluminum / diphosphine are silicon 4ppm, benzene 70
It was 0 ppm.

Benzene was no longer detected after 4 hours. Silicon was not detected after 6 hours.

After all impurities are no longer detected,
Add trimethylaluminum / diphosphine adduct 5
Trimethylaluminum was distilled off and separated by heating to 140 ° C with a torr. Impurities in the obtained trimethylaluminum were 0.3 ppm or less for silicon and 1 ppm or less for benzene.

[0023]

According to the present invention, the low boiling point impurities in the organometallic compound can be continuously removed by flowing an inert carrier gas. Furthermore, by monitoring the impurities in the carrier gas, even those with no experience can be efficiently purified, which is extremely effective in producing the electro-organic metal compound.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a refining device used in the present invention.

[Explanation of symbols]

 1 Flowmeter 2 4-necked flask 3 Stirrer 4 Mantle heater 5 Nitric acid trap 6 FID detector for gas chromatogram 7 Tape heater

[Procedure amendment]

[Submission date] December 15, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

[0023]

According to the present invention, the low boiling point impurities in the organometallic compound can be continuously removed by flowing an inert carrier gas. Furthermore, by monitoring the impurities in the carrier gas, even those with no experience can be efficiently purified, which is very effective in producing high-purity organometallic compounds for electronic materials.

Claims (2)

[Claims] 1. The purification condition is monitored by heating an organometallic compound to remove impurities having a low boiling point using an inert carrier gas, and measuring impurities in the carrier gas with time. A method for purifying an organometallic compound. 2. The organometallic compound has the general formula R _a MX _3-a.
(Wherein R is an alkyl group having 1 to 4 carbon atoms, M is aluminum, gallium or indium, X is halogen, and a is an integer of 2 or 3) or an adduct thereof. A method for purifying an organometallic compound according to claim 1.