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

CVD silicon films were deposited from SiH4 pyrolysis on amorphous SiO2 layers heated at various temperatures in the range 560-620 degrees C, and on amorphous SiNx or polycrystalline silicon layers at 580 degrees 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-Sig substrates. For intermediate temperatures (570 or 580 degrees C), the silicon films are crystallized near the a-Sig substrate and then amorphous up to the surface, when they are entirely amorphous on a-SiNx or c-Si substrates as shown elsewhere by TEM and SEM observations. X.P.S. valence band spectra, core levels photoelectrons and SiKL2,3L2,3 Auger transitions examinations, have shown that a lower growth rate of the silicon films on the a-SiO2 substrate at 570 or 580 degrees C leads to the formation of nanocrystallized silicon deposits at the early stage of the deposition. For a-SiNx substrate, a higher growth rate was observed at the first stage of the deposition, at 580 degrees C. These results can contribute to the understanding of the relationship between the structure changes of the deposit and the nature of the substrates.