Corner effects in vertical MOSFETs

Two kinds of corner effects existing in vertical channel gate-all-around (GAA) MOSFETs have been investigated via three-dimensional (3D) and two-dimensional (2D) simulations. Through comparison between the gate-all-around (GAA) and double-gate (DG) vertical transistors, it is found that the kind of corner effect caused by conterminous gate plays contrary roles in the GAA vertical transistors. It can suppress the leakage current at low channel doping while enhance the leakage current at high channel doping. The study of another kind of corner effect, which exists in the terminal of the channel, shows that D-top structure (drain on the lop of device pillar) of vertical transistor has much lower leakage current and better DIBL effect immunity than S-top structure (source on the top of device pillar).