Low-pressure silicon epitaxy

The deposition process of epitaxial layers on Si substrates under low-pressure conditions has been studied with respect to bipolar devices for VLSI. Epitaxial deposition was carried out in the temperature range from 850 to 1060°C and in the pressure range from 30 to 760 torr with SiH4and SiH2Cl2as Si sources. By reducing the reaction pressure from 760 to 40 torr, the reaction temperature can be lowered about 100 to 150°C, image transfer and quality of buried structures to the surface of the epi-layer will be improved, and autodoping can be reduced drastically.