Diffusion of Indium Implanted in Silicon Oxides

Abstract

Indium atoms were implanted into silicon oxides to study indium diffusion during annealing and deposition processes. In the thermal oxide, the peak indium concentration decays without marked profile broadening, suggesting that a large fraction of indium is immobile during annealing in nitrogen. Oxygen ambient was found to reduce the decay of the indium peak in thermal oxide. The tail diffusion of indium was observed in thermal oxide after chemical vapor deposition using tetraethoxysilane (TEOS) or SiH4 as the precursor. The tail diffusion increases as TEOS oxide replaces thermal oxide. However, performing densification annealing before indium implantation reduces the tail diffusion in TEOS oxide. The tail diffusion indicates an increase in the concentration of mobile indium atoms. Experimental results suggest that hydrogen from deposition processes is important in indium tail diffusion.