Remote Surface Roughness Scattering in FDSOI devices with high-kappa/SiO₂ gate stacks

We investigate remote surface scattering (RSR) by the SiO$_2$/HfO$_2$ interface in Fully-Depleted Silicon-on-Insulator (FDSOI) devices using Non-Equilibrium Green's Functions. We show that the RSR mobility is controlled by cross-correlations between the surface roughness profiles at the Si/SiO$_2$ and SiO$_2$/HfO$_2$ interfaces. Therefore, surface roughness and remote surface roughness can not be modeled as two independent mechanisms. RSR tends to enhance the total mobility when the Si/SiO$_2$ interface and SiO$_2$ thickness profiles are correlated, and to decrease the total mobility when they are anti-correlated. We discuss the implications for the high-$\kappa$/Metal gate technologies.