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

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

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