Impact of Surface Orientation on the Sensitivity of FinFETs to Process Variations—An Assessment Based on the Analytical Solution of the Schrödinger Equation

This paper investigates the impact of surface orientation on V_th sensitivity to process variations for Si and Ge fin-shaped field-effect transistors (FinFETs) using an analytical solution of the Schrödinger equation. Our theoretical model considers the parabolic potential well due to short-channel effects and, therefore, can be used to assess the quantum-confinement effect in short-channel FinFETs. Our study indicates that, for ultrascaled FinFETs, the importance of channel thickness (t_ch) variations increases due to the quantum-confinement effect. The Si-(100) and Ge-(111) surfaces show lower V_th sensitivity to the t_ch variation as compared with other orientations. On the contrary, the quantum-confinement effect reduces the V_th sensitivity to the L_eff variation, and Si-(111) and Ge-(100) surfaces show lower V_th sensitivity as compared with other orientations. Our study may provide insights for device design and circuit optimization using advanced FinFET technologies.