Improvement of Gate Oxide Integrity Characteristics in CZ-Grown Si Crystals by H2 annealing

Abstract

ABSTRACTThe mechanism of improvement in gate oxide integrity (GOI) characteristics by H2 annealing in CZ-grown Silicon wafers was investigated. Grown-in defects that are considered to degrade GOI and which can be detected correlatively as 0.1 μm level size pits appearing after SC-1 cleaning, decrease drastically by H2 annealing, while other inert gases, i.e., N2 and Ar, do not exhibit such effect. Besides, H2 annealing shrinks or extinguishes oxygen precipitates significantly, while other gases do not. On the other hand, oxygen outdiffusion is exactly the same among H2, N2 and Ar annealing. From these results, it was concluded that the dominant mechanism for GOI characteristics improvement by H2 annealing is due to decomposition of the grown-in defects having Si-O bonding by the reduction reaction between Si-O bonding and hydrogen, and not due to a mere thermal decomposition enhanced by oxygen outdiffusion.