A highly threshold Voltage-controllable 4T FinFET with an 8.5-nm-thick Si-fin channel

Highly threshold voltage (V_th)-controllable four-terminal (4T) FinFETs with an aggressively thinned Si-fin thickness down to 8.5-nm have successfully been fabricated by using an orientation-dependent wet-etching technique, and the V_th controllability by gate biasing has systematically been confirmed. The V_th shift rate (γ=-δV_th/δV_g2) dramatically increases with reducing Si-fin thickness (T_Si), and the extremely high γ=0.79 V/V is obtained at the static control gate bias mode for the 8.5-nm-thick Si-fin channel device with the 1.7-nm-thick gate oxide. By the synchronized control gate driving mode, γ=0.46 V/V and almost ideal S-slope are achieved for the same device. These experimental results indicate that the optimum V_th tuning for the high performance and low-power consumption very large-scale integrations can be realized by a small gate bias voltage in the ultrathin Si-fin channel device and the orientation-dependent wet etching is the promising fabrication technique for the 4T FinFETs.