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This paper investigates the impact of surface orientation on Vth 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 (tch) variations increases due to the quantum-confinement effect. The Si-(100) and Ge-(111) surfaces show lower Vth sensitivity to the tch variation as compared with other orientations. On the contrary, the quantum-confinement effect reduces the Vth sensitivity to the Leff variation, and Si-(111) and Ge-(100) surfaces show lower Vth sensitivity as compared with other orientations. Our study may provide insights for device design and circuit optimization using advanced FinFET technologies.
Date of Publication: Dec. 2010