Shifts in the flatband voltage of metal-oxide-silicon structure due to iodine in SiO₂

We report the observation of positive shifts in the flatband voltage of metal-oxide-silicon structure as a consequence of iodine presence in the oxide. The positive shifts remain stable after thermal processing cycles, typical to very large scale integration, as well as under temperature-voltage stress. This flatband behavior is obtained by direct implantation of iodine into SiO 2 and subsequent anneal in the inert ambient. In contrast, if Si is first implanted with iodine and then oxidized, the resulting flatband shifts are stable, but negative. The shifts of both polarities occur without significant increase in the interface state density. In each case, they are correlated with the presence of iodine in the oxide as determined by secondary ion mass spectrometry.