ABSTRACTIn situ ellipsometry has been applied for monitoring silicon-thin-film growth on a glass substrate in RF-discharge plasma of SiF4+SiH4 diluted with H2 (80%). Polycrystalline silicon films were obtained at substrate temperature of 300°C and RF power density of 500MW/cm2. Volumetric fraction of c-Si increased from 50 to 80% by increasing the SiF4/ (SiF4+SiH4) flow ratio from 0 to 0.5. The fraction of c-Si also increased to 63% by sequential repetition of deposition with SiH4/H2 and etching with SiF4. The etching rate of a-Si was less than that of c-Si. These results suggest that semi-preferential etching of a-Si enhances the increase of c-Si fraction. A gas-phase reaction simulation has suggested that the dominant deposition precursor is SiH3, and the etchant is F in the present condition.
Resonant microwaves probing the spatial afterglow of an RF plasma jet