Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Patent
1989-04-07
1991-05-14
Prescott, Arthur C.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
556 13, 556 14, 556 20, 556 21, 556 22, 556 27, 556 30, 556 64, 556 68, 556 70, 556170, 556174, 427 58, 437 81, C07F 500, C07F 506, C23C 1618, C23C 1620
Patent
active
050157477
DESCRIPTION:
BRIEF SUMMARY
The invention relates to organometallic compounds containing aluminum, gallium or indium as the metals and having a cyclic or bicyclic structure and also to the use of these compounds for preparing thin films or epitaxial layers by gas phase deposition.
The deposition of these layers either from pure elements of group III or from combinations with other elements such as, for example, gallium arsenide, indium phosphide or gallium phosphide can be used for the production of electronic and optoelectronic switching components, compound semiconductors and lasers. The deposition of these layers is carried out from the gas phase.
The properties of these films are dependent on the deposition conditions and the chemical composition of the resulting film.
Suitable gas phase deposition methods are all known methods such as Metallo-Organic Chemical Vapor Deposition (MOCVD), Photo Metallo-Organic Vapor Phase (Photo-MOVP) in which the substances are decomposed by irradiation with UV light, Laser Chemical Vapor Deposition (Laser CVD) or Metallo-Organic Magnetron Sputtering (MOMS). The advantages compared with other methods are controllable layer growth, precise doping control and, due to the atmospheric or reduced pressure conditions, easy handling and uncomplicated production.
The MOCVD method uses organometallic compounds which decompose at a temperature below 1100.degree. C. with deposition of the metal. Typical apparatuses which are currently used for MOCVD consist of a bubbler containing an inlet for the organometallic component, a reaction chamber containing the substrate to be coated and also a carrier gas source which should be inert towards the organometallic component. The bubbler is kept at a constant, relatively low temperature which is preferably above the melting point of the organometallic compound, but far below the decomposition temperature. Preferably, the reaction or decomposition chamber has a very much higher temperature which is below 1100.degree. C. and at which the organometallic compound decomposes completely and the metal is deposited. By means of the carrier gas, the organometallic compound is evaporated and channeled into the decomposition chamber together with the carrier gas. The mass flow of the vapor can be readily regulated and thus allows controlled growth of the thin layers.
Up to now, gas phase deposition was carried out in most cases by using metal alkyls such as, for example, trimethylgallium, trimethylaluminum or trimethylindium. However, these compounds are extremely air-sensitive, self-igniting and some of them decompose even at room temperature. Therefore, complicated safety precautions are required for the preparation, transport, storage and use of these compounds. A few somewhat more stable adducts of metal alkyls with Lewis bases such as, for example, trimethylamine and triphenylphosphine are also known (for example as described in GB 2,123,422, EP-A 108,469 or EP-A 176,537), but those are only of limited use for gas phase deposition due to their low vapor pressures.
The object of the present invention was therefore to find metal alkyl compounds which are easily handled and are stable at room temperature and which can be decomposed from the gas phase, that is metal alkyl compounds which are suitable for the different methods of gas phase deposition.
It has now been found that the intramolecularly stabilized compounds of aluminum, indium and gallium which have a cyclic or bicyclic structure are distinguished by a high resistance to air and oxygen and therefore are easily handled and highly suitable for gas phase deposition.
The invention therefore provides organometallic compounds of the formula I ##STR1## in which R.sup.1 and R.sup.2 independently of one another are each H, a straight-chain or branched alkyl group having up to 7 C atoms, which can be partially or completely fluorinated, a cycloalkyl, alkenyl or cycloalkenyl group having each 3-8 C atoms or an unsubstituted or substituted phenyl group,
The invention further provides the use of compounds of the formula I for gas
REFERENCES:
patent: 4349483 (1982-09-01), Beach et al.
patent: 4816594 (1989-03-01), Wengong et al.
Chem. Abstracts, vol. 54, No. 24346i, (1960).
Erdmann Dietrich
Hartmann Uwe
Heyen Meino
Hostalek Martin
Jurgensen Holger
Merck Patent Gesellschaft mit beschrankter Haftung
Prescott Arthur C.
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