METHOD OF PREPARING HIGH-PURITY MONOSILANE Russian patent published in 1999 - IPC

FIELD: organosilicon compounds and semiconductor engineering. SUBSTANCE: invention aims at preparing high-purity monosilane suitable for fabrication of thin-layer semiconductor products and also at preparing high-purity poly- and monocrystalline silicon suitable for semiconductor and solar engineering. Monosilane is prepared by interaction of silicon metal with an alcohol in presence of catalyst at elevated temperature followed by isolation of desired alkoxysilanes, purification thereof and their catalytic disproportionation to form gaseous monosilane, which is further purified by absorbing impurities and liquid disproportionation products including active catalytic materials, teraalkoxysilane and traces of compounds with Si-H bonds. Resultant monosilane is freed of unreacted alcohol which is recycled into reaction with silicon. Concentrated mixture of alkoxysilanes is subjected to catalytic disproportionation at temperature from -20 to +40 C and reaction time from 1 to 50 hr to release gaseous monosilane, which is further purified by preliminary absorption, whereas, to liquid disproportionation products, alcohol is added and tetraalkoxysilane isolated. The latter is completely hydrolyzed to yield commercial silica sol and alcohol, which is dried with tetraalkoxysilane and returned into reaction with silicon. EFFECT: increased yield of product and its purity. 5 cl, 2 tbl, 4 ex