LOADING EFFECTS DURING NON-SELECTIVE EPITAXIAL GROWTH OF Si AND SiGe

摘要

Loading effects were studied for non-selective epitaxial Si and SiGe films grown by chemical vapor deposition using SiH_4 and GeH_4 at 650℃ and 20 - 80 Torr. The growth rates of Si and SiGe films decreased when about 50% of the substrate surface was covered by SiO_2. While the Si epitaxy showed a growth rate smaller than the polycrystalline Si simultaneously deposited on the surrounding SiO_2, the opposite was true for the growth of SiGe. Further increasing oxide surface coverage did not lead to appreciable change in the growth rates. Neither did the doping concentration change with increasing oxide coverage, when in-situ doping with both p- and n-type dopants was performed. Theoretical calculations showed that the difference in growth rates caused by wafer temperature change due to surface emissivity variation was minor. Therefore, chemical effects were the main causes responsible for the growth rate variations.