AbstractThe photo-chemical vapor deposition (CVD) of SiO2 and SiN2 were investigated using 185 nm light of a low pressure mercury lamp. The film thickness deposited on the substrate was the function of the distance from the substrate to the light source and its relation was investigated by changing the reaction pressure. From these investigations, the space migration length of the active species was estimated, which was, at the processing pressure of 400 Pa, about 10–20 mm. This migration length was confirmed by a model calculation. The step coverage of the film was investigated by the use of a two-dimensional capillary cavity. It was shown that the thickness decayed exponentially with the depth in the cavity. The decay constant did not show temperature dependence. From this result, the surface migration of the active species produced by photo-CVD was reported. To confirm this migration we presented a substrate- size effect of photo-CVD, which became obvious when the substrate size became smaller than the space migration length of the active species. From these results, the film growth mechanism of photo-CVD was discussed.
INVESTIGATION OF GROWTH MECHANISM OF NANOCRYSTALLINE SILICON THIN FILMS PREPARED BY HOT-FILAMENT CHEMICAL VAPOR DEPOSITION