J. Phys. IV France 09 (1999) Pr8-1139-Pr8-1145
XPS study of CVD silicon thin films deposited on various substrates from SiH4 gaseous precursorR. Berjoan1, D. Perarnau1 and B. Caussat2
1 Institut de Science et de Génie des Matériaux et Procédés, IMP, UMR 8521 du CNRS, BP. 5, Odeillo, 66125 Font-Romeu cedex, France
2 Laboratoire de Génie Chimique, UMR 5503 du CNRS, 18 chemin de la Loge, 31078 Toulouse cedex, France
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 SiNx 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-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°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°C. These results can contribute to the understanding of the relationship between the structure changes of the deposit and the nature of the substrates.
© EDP Sciences 1999