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

Flexibly controllable threshold-voltage (Vth) asymmetric gate-oxide thickness (Tox) four-terminal (4T) FinFETs with HfO2[equivalentoxidethickness(EOT)=1.4 nm] for the drive gate and HfO2+thick SiO2(EOT=6.4-9.4 nm) for the Vth-control gate have been successfully fabricated by utilizing ion-bombardment-enhanced etching process. Owing to the slightly thick Vth-control gate oxide, the subthreshold slope (S) is significantly improved as compared to the symmetrically thin Tox4T-FinFETs. As a result, the asymmetric Tox4T-FinFETs gain higher Ionthan that for the symmetrically thin Tox4T-FinFETs under the same Ioffconditions