Comprehensive Understanding of Carrier Mobility in MOSFETs with Oxynitrides and Ultrathin Gate Oxides

Inversion-layer mobility in MOSFETs is quantitatively examined by taking MOSFETs with oxynitride and ultra-thin gate oxides as examples. It was shown that additional Coulomb scattering due to charged impurities in poly-Si gate and due to fixed charges in oxynitride gate oxides is responsible for the mobility degradation in low effective electric field region for ultra-thin gate oxides and oxynitride gate oxides, respectively. For high effective electric field region, the different behavior of inversion-layer mobility between electrons and holes associated with oxynitridation can be reasonably well explained by the appropriate choice of the form of the roughness correlation function. This paper focuses on the fact that Coulomb and surface roughness scattering are key scattering components for the unified understanding of carrier mobility in inversion layers of future MOSFETs.