Remote Surface Roughness Scattering in FDSOI devices with high-$\kappa$/SiO$_2$ gate stacks

TL;DR

This paper studies how remote surface roughness at the SiO2/HfO2 interface affects electron mobility in FDSOI devices, revealing that correlations between surface profiles significantly influence device performance.

Contribution

It demonstrates that remote surface roughness impacts mobility through surface profile correlations, challenging independent modeling of roughness mechanisms in high-$ackslash$kappa/ gate stacks.

Findings

Correlated surface roughness enhances mobility.

Anti-correlated roughness reduces mobility.

Remote surface roughness effects depend on interface correlations.

Abstract

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.