Effect of total deposition pressure on the structure of polycrystalline-silicon films

Abstract

The effect of total deposition pressure on the structure of chemically vapor deposited polycrystalline-silicon films was examined over the pressure range from 10–600 Torr using thermal decomposition of SiH4 in a hydrogen carrier gas in the 625–675 °C temperature range in a cold-wall, lamp-heated reactor. The temperature and deposition rate were kept constant for each set of experiments to isolate the effect of hydrogen on the surface diffusion of the silicon species. Both the amorphous-to-polycrystalline transition and the dominant crystal orientation depend on the total deposition pressure; however, the dependence is only moderate. Differences in gas purity and system integrity between different reactors also play a strong role in controlling the structure.