Fabrication of dielectrically isolated microelectronic semiconductor circuits utilizing selective growth by low pressure vapor deposition

A method for the fabrication of a semiconductor device comprising the steps of:

• (a) forming a patterned layer of silicon nitride on the surface of a monocrystalline semiconductor body;
• (b) contacting said body and patterned layer with a vaporous or gaseous semiconductor compound at a pressure between 1 torr and 100 torr, at a temperature between 700.degree. C. and 1420.degree. C. to cause selective epitaxial deposition of monocrystalline semiconductor on said body, and concurrent deposition of polycrystalline semiconductor on said patterned layer;
• (c) controlling the ratio of mono to poly growth rates to obtain substantially faster growth of mono than poly;
• (d) continuing such growth until the single crystal deposit becomes substantially thicker than the combined thickness of the nitride plus the poly deposited thereon;
• (e) oxidizing the combined deposits, until the poly deposit is substantially fully oxidized, at which time the oxide surface of the oxidized mono becomes substantially coplanar with the oxide surface of the oxidized poly;
• (f) then fabricating one or more components in the mono deposit.