XPS study of CVD silicon thin films deposited on various substrates from SiH₄ gaseous precursor

Abstract
CVD silicon films were deposited from SiH₄ pyrolysis on amorphous SiO₂ layers heated at various temperatures in the range 560-620°C, and on amorphous SiN_x or polycrystalline silicon layers at 580°C. According to the substrate temperature, the silicon films can be completely crystallized for the highest temperature, or amorphous for the lowest temperature, in the case of a-SiO₂ substrates. For intermediate temperatures (570 or 580°C), the silicon films are crystallized near the a-SiO₂ substrate and then amorphous up to the surface, when they are entirely amorphous on a-SiN_x or c-Si substrates as shown elsewhere by TEM and SEM observations. X.P.S. valence band spectra, core levels photoelectrons and SiKL_2,3L_2,3 Auger transitions examinations, have shown that a lower growth rate of the silicon films on the a-SiO₂ substrate at 570 or 580°C leads to the formation of nanocrystallized silicon deposits at the early stage of the deposition. For a-SiN_x substrate, a higher growth rate was observed at the first stage of the deposition, at 580°C. These results can contribute to the understanding of the relationship between the structure changes of the deposit and the nature of the substrates.