STUDY OF DEFECTS INDUCED BY HIGH-ELECTRIC-FIELD STRESS INTO A THIN GATE OXIDE (11 NM) OF METAL-OXIDE-SEMICONDUCTOR CAPACITORS

The creation of defects into a thin gate oxide (11 nm) of polycrystall ine silicon-oxide-semiconductor capacitors by electron injection Fowle r-Nordheim effect, their electric nature, and their behavior when stre ssed samples are submitted to a white-light illumination in the invers ion regime are studied. It is shown that low-electron-injected fluence s cause creation of positive charges and that high fluences generate n egative charges in the bulk of the oxide. Current-voltage characterist ics 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 neg ative charges are localized close to the injecting electrode and the p ositive charges near to the Si/SiO2 interface. These positive charges are annihilated by light illumination without interface-state generati on when stressed samples are biased in the inversion regime. Interface states do not show any saturation and their analytical expression ver sus injected charge contains two different terms which correspond to t wo different mechanisms of interface-state creation.