Independent double-gate FinFETs with asymmetric gate stacks

Flexibly controllable threshold voltage (Vth) asymmetric gate oxide thickness (Tox) independent double-gate (DG) FinFETs (4T-FinFETs) have been demonstrated. Thin drive-gate oxide (HfO2 or SiON or SiO2) and slightly thick Vth-control-gate oxide (thick SiO2+drive-gate oxide) have been successfully incorporated into the 4T-FinFETs by utilizing the ion-bombardment-enhanced etching of SiO2. It was experimentally confirmed that, all the asymmetric Tox 4T-FinFETs give the significantly improved subthreshold slope and thus gain higher on-current as compared to the symmetric one. Simulation results showed that the asymmetric Tox 4T-FinFETs are advantageous even in 20-nm-gate-length region.