Analysis of Negative Capacitance UTB SOI MOSFETs considering Line-Edge Roughness and Work Function Variation

We analyze the threshold voltage (Vt) and switching time (ST) variations of negative capacitance UTB SOI MOSFETs (NC-SOI) and UTB SOI MOSFETs considering line-edge roughness (LER) and work function variation (WFV). Compared to SOI, NC-SOI exhibits smaller LER induced Vt variations (σVt) and comparable WFV induced Vt variations. LER induced σVt can be suppressed by negative capacitance, while WFV induced σVt cannot be suppressed by negative capacitance. For considering LER, NC-SOI with larger subthreshold swing (SS) and worse short channel effect exhibits better capacitance matching, larger voltage gain (Av), and larger threshold voltage difference (Vt
_NC-SOI
-Vt
_SOI
), which mitigates the σVt. For NC-SOI MOSFETs, WFV induced σVt (=16.2mV) is larger than LER induced σVt (=3.8mV). For SOI MOSFETs, WFV and LER show comparable σVt. However, for both NC-SOI and SOI MOSFETs, LER induced ST variations are larger than the WFV induced ST variations. This is because transition charge (ΔQ) and effective drive current (Ieff) are positively correlated for considering WFV and negatively correlated for considering LER. Compared with SOI, NC-SOI considering LER and WFV exhibits smaller ST variations due to larger Ieff.