Investigation of Fixed Oxide Charge and Fin Profile Effects on Bulk FinFET Device Characteristics

The effect of positive fixed oxide charge (Q_f) on the electrical characteristics of bulk FinFET devices is investigated and newly addressed as a Fin scaling detractor. The aggressively scaled Fin width leads to abnormal subthreshold slope (SS) degradation in nMOS devices even with a long channel length, while pMOS is free of such degradation. This observation is reproduced and analyzed by a well-calibrated TCAD simulation deck with Q_f introduced. A new Fin profile suppressing the Q_f effect is proposed, and the benefits of the new profile are predicted in terms of variability reduction and mobility improvement, as well as Q_f immunity.