Demonstration of Asymmetric Gate-Oxide Thickness Four-Terminal FinFETs Having Flexible Threshold Voltage and Good Subthreshold Slope

Flexibly controllable threshold-voltage (V th ) asymmetric gate-oxide thickness (T ox ) four-terminal (4T) FinFETs with HfO 2 [equivalentoxidethickness(EOT)=1.4 nm] for the drive gate and HfO 2 +thick SiO 2 (EOT=6.4-9.4 nm) for the V th -control gate have been successfully fabricated by utilizing ion-bombardment-enhanced etching process. Owing to the slightly thick V th -control gate oxide, the subthreshold slope (S) is significantly improved as compared to the symmetrically thin T ox 4T-FinFETs. As a result, the asymmetric T ox 4T-FinFETs gain higher I on than that for the symmetrically thin T ox 4T-FinFETs under the same I off conditions