4-terminal FinFETs with high threshold voltage controllability

For future ultra-low power circuit designs, flexible V_th control will inevitably be required. To meet this requirement, four-terminal (4-T) DG MOSFETs are promising, thanks to the static and/or dynamic V_th controllability by one of the double gates. Recently, we demonstrated independent double gate FinFETs, fabricated by using orientation-dependent wet etching. This method has great advantages in forming precise Si-fins with an atomically flat channel surface. In this paper, we present the successful fabrication of the ultra-thin Si-fins by wet etching, and the fine separated double gates. We show the excellent V_th controllability of the fabricated 4-T FinFETs by reducing the Si-fin thickness (T_Si) down to 13 nm. We also discuss the T_Si dependence of the V_th tunable range on the T_Si.