Study of defects induced by high-electric-field stress into a thin gate oxide (11 nm) of metal-oxide-semiconductor capacitors

Abstract

The creation of defects into a thin gate oxide (11 nm) of polycrystalline silicon-oxide-semiconductor capacitors by electron injection Fowler–Nordheim effect, their electric nature, and their behavior when stressed samples are submitted to a white-light illumination in the inversion regime are studied. It is shown that low-electron-injected fluences cause creation of positive charges and that high fluences generate negative charges in the bulk of the oxide. Current-voltage characteristics have been performed in the accumulation and the inversion regimes before and after electron injection. These characteristics show a very weak shift and a small distortion which seem to indicate that the negative charges are localized close to the injecting electrode and the positive charges near to the Si/SiO2 interface. These positive charges are annihilated by light illumination without interface-state generation when stressed samples are biased in the inversion regime. Interface states do not show any saturation and their analytical expression versus injected charge contains two different terms which correspond to two different mechanisms of interface-state creation.