Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Patent
1997-07-14
1999-03-23
Wilson, James O.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
556 1, 556 9, 556 13, 556 27, 556 64, 556 81, 556101, 556102, 556170, 556400, 546 2, 546 12, 544225, 540310, C07F 722
Patent
active
058862030
DESCRIPTION:
BRIEF SUMMARY
This application is the U.S. National Stage of International application Ser. No. PCT/GB95/02087, filed Sept. 4, 1995, which derives its priority from Great Britain Patent applications Ser. No. 9508702.9, filed Apr. 28, 1995 and 9417707.8, filed Sept. 2, 1994.
DESCRIPTION
This invention concerns metalorganic compounds, especially metalorganic compounds used in the growth of semiconductor layers by vapour phase epitaxial techniques, such as by chemical beam epitaxy, MOVPE, or ALE.
Metalorganic precursors used in semiconductor growth are generally synthesised by reacting a Grignard reagent such as an alkyl magnesium halide RMgX or an alkyl lithium compound with a metal halide. The formation of the Grignard reagent and its subsequent reaction with a metal halide to form the precursor are carried out in an oxygen containing solvent, typically an ether. Subsequent purification processes are then performed to remove the oxygen containing ether solvent and other impurities from the metalorganic precursor.
Unfortunately residual trace amounts of ether can result in oxygen contamination of semi-conductor structures grown using the above prepared precursors. Consequently, there is a deleterious effect on the properties of the semiconductor structures.
The existence of metalorganic amine adducts, has been disclosed in for example the reports of Henrickson C. H. et al (Inorganic Chemistry, vol. 7, no 6 1968 pages 1047-1051) and Stevens, L. G. et al (Journal of Inorganic and Nuclear Chemistry, vol. 26, 1964, pages 97 -102).
An object of this invention is to provide a method of preparing metalorganic compounds that avoids the above-mentioned disadvantages.
According to this invention there is provided a process for preparing a metalorganic compound by reacting a Grignard reagent with the metal halide, characterised in that said reaction is carried out in an amine solvent.
The Grignard reagent for use in the process of the invention is preferably prepared in an amine solvent, especially the amine to be used in preparing the metalorganic compound.
The amine is preferably a tertiary amine such as, for example, a tertiary alkyl amine or a tertiary heterocyclic amine. Amines for use in the invention are preferably liquid at room temperature, typically 18.degree. to 20.degree. C. Tertiary alkyl amines for use in the invention preferably have the formula ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 are alkyl groups having from 1 to 4 carbon atoms and wherein R.sup.1, R.sup.2, and R.sup.3 may be the same or two of R.sup.1, R.sup.2 and R.sup.3 may be the same. Preferred alkyl amines for use in the invention are triethylamine and dimethylethylamine.
Suitable heterocylic amines for use in the invention may include pyridine, 2H-pyrrole, pyrimidine, pyrazine, pyridazine, 1,3,5-triazine and hexahydrotriazine.
The Grignard reagent may be prepared in any suitable way, typically by reaction of magnesium with an alkyl halide, wherein the alkyl group is that required for the metalorganic compound.
Metalorganic compounds that may be prepared in accordance with the invention include alkyl compounds of Group II, Group III and Group V metals. Examples of such compounds include dialkyl zinc, dialkyl cadmium, trialkyl aluminium, trialkyl gallium, trialkyl indium, trialkyl phosphorus, trialkyl arsenic and trialkyl antimony.
It is believed that the process of the present invention results in an adduct of the metalorganic compound with the amine. The formation of this adduct permits the removal of volatile metallic and nonmetallic microimpurities from the metalorganic compound. Impurities may be readily removed from the adduct by distillation. The adduct may be split by removal of the amine, such as by heating, to provide the metalorganic compound alone for some purposes, such as a precursor for MOVPE or CBE. Alternatively the adduct itself may be used as a precursor for the deposition of, for example Group III-V or II-VI layers, such as gallium arsenide, aluminium gallium arsenide and zinc selenide, by MOVPE, CBE and other vapour phase epitax
REFERENCES:
patent: 4812586 (1989-03-01), Mullin et al.
Inorganic Chemistry, vol. 7, No. 6, 1968, Henrickson, C.H. et al., "Lewis Acidity of Alanes. Interactions of Trimethylalane with Amines, Ethers, and Phosphines, " pp. 1047-1051.
Journal of Inorganic and Nuclear Chemistry, vol. 26, 1964, Stevens, L.G. et al., "Organogalium Compounds III. The Heat of Dissociation of Triethyl and Trivinylgallium Addition Compounds," pp. 97-102.
Journal of the Chemical Society, Dalton Transactions, 1988, Foster, D.F. et al., Synthesis and Thermal Properties of Adducts of Trimethylindium with Nitrogen-Containing Lewis Bases, pp. 7-11
Chemische Berichte, vol. 122, 1989, Neumuller, B., "Synthese und Eigenschaften von iPr.sub.2 InCl, iPrlnCl.sub.2 und (iPr.sub.2 InNHtBu).sub.2," pp. 2283-2287
Chemical Abstracts , vol. 114, No. 21, May, 1991, Hoffman, G.G. et al., "Synthesis, Properties, and some reactions of Isopropylgallium Haldies and Tris(isopropyl)gallane," pp. 838.
Freer Richard William
Jones Anthony Copeland
Martin Trevor
Rushworth Simon Andrew
Whittaker Timothy John
Secretary of State For Defence Acting Through His Defence Evalua
Wilson James O.
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