Suppression of Stress-Induced Leakage Current of Wet and Dry SiO2 by SiD4 Poly-Si Gate Electrode

Abstract

In this paper, we report on the effect of deuterated poly-Si deposition on stress-induced leakage current (SILC) under Fowler–Nordheim (F–N) electron injection. A deuterated poly-Si gate electrode was deposited on wet and dry thin gate oxide films by utilizing deuterated monosilane (SiD4) gas, as a substitute for hydrogenated monosilane (SiH4) gas. As a result, it was found that SILC values of both wet and dry oxides were clearly suppressed by the deuterated poly-Si gate electrode. Experimental results for the depth profiles of the introduced-deuterium atoms indicated that a large amount of deuterium is introduced into the gate oxide films after the deuterated poly-Si deposition. Furthermore, it was found that hydrogen concentration in a wet oxide film decreases by high-temperature deuterium annealing, while deuterium concentration increases. It is inferred that both high concentration of deuterium and high-temperature annealing for gate doping after poly-Si deposition bring about the suppression of SILC due to the efficient replacement of hydrogen with deuterium in gate oxide films.