Fluctuation Analysis of Parasitic Resistance in FinFETs With Scaled Fin Thickness

Measurement-based analysis of the parasitic resistance $(R_{\rm para})$ of FinFETs was extended to investigation of $R_{\rm para}$ fluctuation, which could cause severe on-current variation. $R_{\rm para}$ was obtained from the intercept in the linear relationship between measured on-resistance and gate length for FinFETs of various dimensions. A significant increase in $R_{\rm para}$ is observed for fin thickness below 25 nm due to dopant loss from the ultrathin extension during processing. $R_{\rm para}$ variation was evaluated for 45 FinFETs with an average fin thickness of 16 nm. Significant $R_{\rm para}$ variation is observed and correlates with the variation of fin thickness.