Effect of Border Traps on Electron Mobility of Nano-Scale MOS Devices

It has been recently identified that the near-interfacial oxide trap called `border trap´ can strongly affect the radiation response and long term reliability of irradiated MOS devices. But the existing mobility models used to compute radiation induced mobility degradation does not include border traps. Also the quantum mechanical structural confinement plays an important role in the reliability of MOS devices. The aim of this paper is to develop analytical model that accurately predicts mobility of the extremely small silicon thickness MOS devices placed under the radiation. The developed model includes surface roughness, surface mode optical phonon scattering, scattering due to silicon thickness fluctuations and phonon scattering with structural confinements and also the effect of border traps apart from interface and oxide traps. The reported experimental data is extrapolated for the nano-scale devices. From this data, mobility of the irradiated MOSFETs is computed using the developed expression. The results obtained are compared with Sentaurus TCAD simulations and also against numerous reported experimental results. A close match between the developed model, TCAD simulation results and experimental results validate our approach. The study undertaken would help to accurately estimate the radiation induced mobility degradation in MOS devices.