Impacts of Equivalent Oxide Thickness Scaling of TiN/Y₂O₃ Gate Stacks With Trimethylaluminum Treatment on SiGe MOS Interface Properties

Ultrathin equivalent oxide thickness (EOT) scaling of TiN/Y
₂
O
₃
/SiGe gate stacks using a trimethylaluminum (TMA) treatment was studied. In comparison to previously reported high-k/SiGe MOS interfaces utilizing various Ge contents, we obtained an EOT scaling down to 1 nm with ultralow interface trap densities ( D
_it
). In addition, the impact of EOT scaling on the SiGe MOS interface properties has been investigated. We found the stress-induced degradation at the SiGe interface from constant gate biasing can be suppressed by scaling the thickness of Y
₂
O
₃
.