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 SiH
4
and SiH
2
Cl
2
as 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.