A model for NBTI in nitrided oxide MOSFETs without hydrogen or diffusion

The negative bias temperature instability (NBTI) is, arguably, the single most important reliability problem in present day metal oxide silicon field effect transistor (MOSFET) technology. This paper presents a model for NBTI which is radically different from the quite widely utilized reaction diffusion models which dominate the current day NBTI literature. The proposed model is relevant to technologically important nitrided oxide pMOSFETs. The model is clearly not, at least in its entirety, relevant to pure silicon dioxide gate pMOSFETs. Reaction diffusion models involve hydrogen/silicon bond breaking events at the silicon/silicon dioxide interface initiated by the presence of an interface hole, followed by the diffusion of a hydrogenic species from the interface as well as potential rebonding of hydrogen and interface trap defect centers. This model does not invoke hydrogen in any form whatsoever but does simply account for the observed NBTI power law response and provides a reasonably accurate value for this exponent. The model also provides a reasonable explanation for recovery which includes a simple explanation for the extremely rapid rate of recovery at short times. In addition, the model provides a very simple explanation why the introduction of nitrogen greatly enhances NBTI. Finally, the model is consistent with recent electron paramagnetic resonance studies of NBTI defect chemistry.