Enhanced channel mobility at sub-nm EOT by integration of a TmSiO interfacial layer in HfO2/TiN high-k/metal gate MOSFETs

Abstract

Integration of a high-k interfacial layer (IL) is considered the leading technological solution to extend the scalability of Hf-based high-k/metal gate CMOS technology. We have previously shown that thulium silicate (TmSiO) IL can provide excellent electrical characteristics and enhanced channel mobility at sub-nm EOT. This paper presents a detailed analysis of channel mobility in TmSiO/HfO2/TiN MOSFETs, obtained through measurements at varying temperature and under constant voltage stress. We show experimentally for the first time that integration of a high-k IL can benefit mobility by attenuating remote phonon scattering. Specifically, integration of TmSiO results in attenuated remote phonon scattering compared to reference SiOx/HfO2 dielectric stacks having the same EOT, whereas it has no significant influence on remote Coulomb scattering.