Enhanced Channel Mobility at Sub-nm EOT by Integration of a TmSiO Interfacial Layer in HfO2/TiN High-k/Metal Gate MOSFETs

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 SiO_x/HfO₂ dielectric stacks having the same EOT, whereas it has no significant influence on remote Coulomb scattering.