Broad Energy Distribution of NBTI-Induced Interface States in p-MOSFETs with Ultra-Thin Nitrided Oxide

The energy distribution of interface states during NBTI stress of ultra-thin nitrided-oxide p-FETs is studied using a combination of LV-SILC and DCIV measurements. LV-SILC is sensitive to states near the conduction band edge, while DCIV is sensitive to states near mid-gap. The results show that the interface states associated with NBTI in nitrided oxides have a very broad energy distribution. Compared to pure SiO2, the interface state density in nitrided oxide is higher in the upper half of the Si band gap. In addition, generated bulk neutral traps show a poor agreement with the NBTI-induced threshold voltage shift. [Keywords: NBTI, SiO2, oxynitride, p-MOS, SILC, LV-SILC, interface states, bulk traps, mid-gap states, band-edge states, gated diode, DCIV, nitrogen, plasma nitridation]