JP2887145B2 - Method for producing metal alkyl compound - Google Patents

Description

Description of the Invention The present invention in formula I MR ₃ (I) (wherein, M is In, a Ga or Al, and R is a branched chain hydrocarbon, saturated or unsaturated C _{1 to 10} Or a cyclic hydrocarbon group, and R is also a C _6-10
Which can be aryl).

The process according to the invention makes it possible to produce the organometallic compounds of the formula I in particular with high purity and with very good yields.

Metalorganic vapor phase epitaxy is a group III-V substance,
It is of growing importance, with the potential for its use in an increasingly wide range of industrial applications as a method of manufacturing materials such as single crystal layers, particularly for use in semiconductors. For this purpose, the required materials must be produced in the form of high-purity metal alkyl compounds.

In the art, mainly triethyl compounds of indium, gallium and aluminum have been used and are still used today. Recently, the corresponding trimethyl compounds have been increasingly used.

There is relatively large variation in the quality of commercially available metal alkyl compounds. This is especially true for indium materials.

In principle, all known processes for the preparation of such metal alkyl compounds are based on the reaction of the corresponding metal halide with an organometallic alkylating agent. The current state of these technologies can be found, for example, in the following publications: Zeitschrift fr anorganische und allgemeine Che
mie, vol. 267 (1951), pages 39-48, especially pages 39-41 ("Indium
organische Verbindungen ", F.Runge / W.Zimmermann / H.Pf
eiffer / J.Pfeiffer), Zeitschrift fr anorganische und allgemeine Che
mie, 321 (1963), pp. 120-123 (“Darstellungvon ind
ium-Trialkylen ber In-Mg-Legierung oder-Misc
hung ", E. Todt / R. Dtzer), Journal of Organometallic Chemistry, 8 (1967),
427-434 (“Organoindium Chemistry, IA Convenien
t Preparation of Dimethylindium (III) Derivative
s ", HCClark / ALPickard), Inorg. Nucl. Chem. Letters, 9 (1973), pp. 587-589 (" Eine verbesserte Darstellungsmethode fr Indi
umtrimethyl ", P. Krommes / J. Lorberth), and Journal
of the American Chemical Society, 84 (1962), 360
5-3610 (“Organometallic Compounds of Group II
IIThe Preparation of Gallium and Indium Alkyls f
rom Organoaluminum Compounds ", JJEisch).

Taking the case of indium alkyl compounds as an example, the formation of such compounds can also be shown by the following formula (Me = methyl, X =
Cl, Br, I):. .. -InCl 3 + 3MeMgCl → InMe 3 + 3MgCl 2 (Runge , etc.) -2In + 3Mg + 6MeX → 2InMe 3 + 3MgX 2 (Dtzer _{etc.) -InCl 3 + 3LiMe → InMe 3} + 3LiCl (Pickard , etc.) -2In + 3HgMe ₂ → 2InMe ₃ + 3Hg (Krommes / Lorberth) Also, an electrochemical manufacturing method is possible.

Among the known methods, in particular, for example, the first,
The process using the reaction according to the second or third formula has the serious disadvantage that the metal alkyl compounds prepared are obtained as a result of this process in the form of solvent adducts, in particular ether adducts. Such adducts are not themselves suitable for use in epitaxy. They must first of all be free of chemically bound solvents. The conversion to ether-free metal alkyl compounds is usually effected by thermal methods, for example by using strong heating and, if necessary, also under reduced pressure. Because these products are susceptible to decomposition, these treatments involve considerable potential danger.

Other methods, particularly those involving, for example, reactions according to the second, fourth or fifth formulas above, produce metal alkyl compounds with the high purity currently required for epitaxy. I can't. Contamination by trace amounts of metals from the reaction components is practically unavoidable. Furthermore, these methods also use substances which are very toxic and / or highly flammable.

It is therefore an object of the present invention to find a process by which trialkyl compounds of the metals indium, gallium and aluminum can be produced with high purity suitable for the purpose of epitaxy. In particular, this method should be easy to operate without any safety issues,
And also to get a very good product yield,
Must be as good as possible.

The present invention provides a compound of the formula I: MR ₃ (I) wherein M is In, Ga or Al and R is a C _1-10 saturated or unsaturated branched or cyclic hydrocarbon group. And R is also C _6-10
Which can be aryl), which is of the formula II or III: M′MR ₄ (II) M ″ (MR ₄ ) ₂ (III) , M ′ is Li, Na and K, and M ″ is
A compound which does not contain a coordinated ether or ether-type solvent in an inert organic solvent,
A stoichiometrically appropriate amount of the formula IV MX _Z R _3-Z (IV) wherein X is Cl, Br or I and z is 1,2
Or a compound of the formula 3) to produce an organometallic compound of the formula I, which is separated from the remaining organometallic or magnesium halide by distillation. is there.

Surprisingly, by using this type of process, the organometallic compounds of the formula I can be prepared with a particularly high purity and also in a high yield, particularly suitable for epitaxy purposes. It was found that it could be manufactured.

The invention furthermore relates to the use of the organometallic compounds produced by this method as raw materials for the production of semiconductor layers, in particular by using vapor phase epitaxy.

In other formulas, including Formula I, the group R is a saturated or unsaturated branched or cyclic hydrocarbon group of 1 to 10 C atoms, which may be the same or different, or R is , An aromatic group having 6 to 10 C atoms, especially methyl, ethyl, n- or i-propyl,
n-, sec-, i- or t-butyl and each isomer form of pentyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclopropenyl, cyclobutenyl, cyclopentadienyl, cyclooctatetaniel, dec-1-
Ene-3-ynyl, phenyl, tolyl, xylyl or trimethylphenyl. Particularly preferred compounds of the formula I are the corresponding compounds wherein R present in the molecule is methyl or ethyl.

The process according to the present invention is a process using an organometallic or magnesium tetraalkylmetal complex compound represented by the formula II or III as a raw material, respectively.

As is evident when compared to the metal alkyl compounds of the formula I, prepared in a conventional manner, these compounds are, as a result of their preparation, coordinated solvents contained in these compounds, for example: The very easy removal of ether or ether type solvents has the particular advantage that substantially no residue is left. The removal of the bound ether or ether type solvent can even be carried out at room temperature under reduced pressure. About 100 ℃
Mild heating to facilitate this removal. Another effective method for removing ether is to simply wash these compounds with an inert organic solvent, if necessary, in combination with drying under reduced pressure. An inert organic solvent is intended to mean a substance that does not contain a coordinatively active group. These solvents are mainly aliphatic solvents such as pentane and hexane, and aromatic solvents such as benzene, toluene, xylene or mesitylene.

A preferred method for preparing the ether-free starting compounds of formulas II and III is to heat gently under reduced pressure, wash with pentane or benzene, and then dry under reduced pressure.

At least some of the starting compounds of the formulas II and III are known, and these compounds can be produced by methods known per se. That is, as an example, “Journal of Organometallic Chemis
try ", 37 (1972), pp. 1-8, K. Hoffmann / E. Weiss,
The crystal structure of the production as well as Li (InMe ₄₎ and Na (InMe ₄₎ of the alkali metal tetramethyl indium compounds have been reported.

In general, for the process according to the invention, formula II and formula II
The starting compound represented by I can be produced by reacting the corresponding metal trihalide or the corresponding metal-halogen-alkyl compound with a stoichiometrically appropriate amount of an alkali metal alkyl compound or dialkyl magnesium. The term "stoichiometrically suitable" refers to the use of an alkylating agent in excess of one stoichiometric equivalent based on the halogen content of the metal-halogen compound or metal-halogen-alkyl compound, such as And the formula II
Or the formation of an alkali metal or magnesium tetraalkyl-metal compound of formula III, respectively.

Quite generally, these reactions can be represented in the form: Suitable starting materials for this reaction are trihalides of indium molybdenum, gallium and aluminum, especially their trichlorides, but their alkyl-dihalogen compounds or their dialkyl-monohalogen compounds can also be used advantageously. As the alkyl base,
Preferably, lithium alkyl compounds, especially methyl lithium, are used.

This reaction is usually performed in an ether type solvent,
As the pressure, standard atmospheric pressure can be used, and as the temperature, a temperature ranging from room temperature to the boiling point of the solvent used can be used. The solvents used are suitably dialkyl ethers such as diethyl ether, in particular polyethers such as ethylene glycol dimethyl or diethyl ether or the corresponding homologs, and cyclic ethers such as tetrahydrofuran or dioxane.

This process for obtaining tetramethyl compounds of the formula II or III and for using these compounds as intermediates in the preparation of the desired trimethyl compounds is described in the above-mentioned scientific book by Hoffmann and Weiss. It cannot be guessed and the Pick
Nor is it comparable to the known reaction of indium chloride with methyllithium according to the formula of ard et al. In the case of this conventional reaction, trimethylindium is obtained in the form of a very stable etherate adduct, which requires thermal removal of the ether. Instead of the known 1: 3 reaction, in the process according to the invention, a 1: 4 reaction is carried out, which leads to a chemical displacement of the ether. Thus, it will be substantially easier to obtain a compound of formula II or III, which is free of solvent.

In the actual reaction of the process according to the invention, an ether-free organometallic or magnesium tetraalkyl-metal compound of the formula II or III,
Reaction with a stoichiometrically applicable amount of a compound of formula IV produces the desired product I. As the compound represented by the formula IV, it is preferable to use a raw material used for producing the compound represented by the formula II or the formula III. Furthermore, it is preferred to use indium, gallium or aluminum trihalides, especially trichlorides. formula
The stoichiometric amount of the compound represented by IV depends on its halogen content and whether it is reacted with an alkali metal tetraalkyl-metal compound or with a magnesium tetraalkyl-metal compound. .

Quite usually, this reaction to give the desired product can be represented in the form: In the process according to the invention, it is particularly preferred to react a lithium tetraalkyl-metal compound as a compound of the formula II with a corresponding metal-trihalogen compound as a compound of the formula IV. Formula II at this time
The stoichiometric ratio of the compound of Formula IV to the compound of Formula IV is 3: 1.

The reaction is usually performed in an inert solvent as described above for the purification of the compound of formula II or III. Suitable solvents are again pentane, hexane, benzene, xylene or mesitylene. Similarly, commonly used pressures are usually atmospheric, and commonly used temperatures are usually from room temperature to the boiling point of the solvent. Any heat that may be generated during the reaction can be easily removed by cooling. The reaction is preferably
Perform at room temperature. In special cases, the reaction can also be carried out without the use of solvents, which simplifies the subsequent purification of the product.

At the completion of the reaction, the resulting organometallic compound of formula I can be separated from the reaction mixture by vertical distillation. This is preferably carried out by first distilling off the solvent under reduced pressure and then distilling the desired product from the residual organometallic or magnesium halide at atmospheric pressure. Fractional distillation makes it possible to obtain the organometallic compounds of the formula I with the remarkably high purity currently required for epitaxy purposes.

These products are particularly suitable as raw materials for the production of layers of semiconductor material by vapor phase epitaxy (MOCVD).

EXAMPLE All treatments must be carried out with strict exclusion of air and moisture, for example in a purified argon atmosphere. The solvents used must be conventional and free of traces of air and moisture.

Example 1 9.07 g (= 0.04 mol) of indium trichloride was
With stirring and cooling with ice water, lithium tetramethyl indium 2 containing no trace amount of ether
2.3 g (= 0.122 mol) are added in portions, washed with benzene or pentane and then dried under reduced pressure. 200 ml of benzene is used as a reaction solvent. When the exothermic reaction has subsided, the mixture is refluxed for a further 24 hours.
Subsequently, the solvent is distilled off under reduced pressure and the colorless residue is subjected to a fractional distillation treatment. After removing a small amount of the initial effluent, 21.5 g of trimethylindium (= 82% of theory) have a boiling point of ₇₆₀ = 13
At 3.5 ° C., it is obtained as the expected product.

Example 2 28.6 g (0.29 mol) of dimethylgallium chloride was
With stirring and cooling, 40.1 g (= 0.29 mol) of lithium tetramethylgallium dried under reduced pressure is added little by little. After stirring for 1 hour at room temperature, the mixture is fractionally distilled. Product: 85.8 g of trimethylgallium (theoretical 7
0%).

Example 3 15 g (0.11 mol) of aluminum trichloride was dried under reduced pressure while stirring and cooling with 49.7 g (= 0.33 mol) of lithium tetraethylaluminum and 500 ml of hexane.
Add little by little to the suspension. After stirring at room temperature for 3 hours, the solvent is distilled off. The colorless residue is subjected to a fractional distillation.
Product: 48 g of triethylaluminum (= theoretical 92
%).

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Wuolfram, Peter Ludwig-Kirchshijtrath 11a, D-1000 Berlin 15, Germany

Claims (6)

(57) [Claims] 1. A compound of the formula I: MR ₃ (I) wherein M is In, Ga or Al, and R is a C _1-10 saturated or unsaturated branched hydrocarbon group or cyclic hydrocarbon group. A hydrogen group and R is also a C _6-10
A process for preparing an organometallic compound of the formula II or III: M′MR ₄ (II) M ″ (MR ₄ ) ₂ (III), wherein M ′ Is Li, Na and K, and M ″ is Mg), and contains no solvent for the coordinated ether.
The compound is represented by a stoichiometric amount of the formula IV: MX _Z R _3-Z (IV), wherein X is Cl, Br or I and z is a number of 1, 2 or 3. A process for producing an organometallic compound by reacting with a compound to produce an organometallic compound of the formula I and separating the product from the remaining organometallic halide or magnesium halide by distillation. 2. The method according to claim 1, wherein the compounds of the formulas II and III are prepared by one or more of the following methods: heating under vacuum, washing with an inert organic solvent, drying under vacuum, 2. The method of claim 1, wherein the ether solvent has been removed. 3. The compound of the formula II or III is converted to the ether-free form by heating at 100 ° C. under vacuum and then washed with an aliphatic or aromatic solvent. The method according to claim 2, which has been post-purified. 4. The compound of formula II is a lithium tetraalkyl-metal compound and the compound of formula IV is a 3: 1 corresponding metal-trihalogen compound.
The method according to claim 1, wherein the reaction is carried out at a ratio of: 5. The method according to claim 1, wherein the reaction is an aliphatic or aromatic solvent,
Preferably pentane, hexane, benzene, toluene,
5. The process according to claim 1, wherein the process is carried out in xylene or mesitylene. 6. When the reaction is complete, the solvent is distilled off from the reaction mixture by means of vacuum distillation and the organometallic compound of the formula I is obtained by means of fractional distillation under atmospheric pressure.
6. The method according to any one of claims 1 to 5, wherein the method is isolated in a highly pure form.