Study of the poly/epi kinetic ratio in SiH 4 based chemistry for new CMOS architectures

Abstract

In this work, we studied the effect of the deposition temperature, partial pressure and crystallite texture on the poly/epi growth rate ratio by decomposition of silane. Deposition was performed by rapid thermal chemical vapor deposition (RTCVD) in the temperature range 590< T<720 °C and in the silane partial pressure range 0.14< P<1.7 Torr. For monocrystalline silicon, we have observed that growth rate is proportional to the silane partial pressure. On the other hand, we have shown that for “polysilicon” the growth rate ratio slightly increases with partial pressure, like the amorphous content. For a fixed temperature, we found that amorphous content is related to the silane partial pressure and that the growth rate ratio is strongly dependent on the polycrystal roughness. It results in a non-monotonous trend of growth rate ratio versus silane partial pressure. From our experiments, we have obtained growth rate ratio varying from 1.2 to 2.5.