Simple S/D Series Resistance Extraction Method Optimized for Nanowire FETs

The conventional source/drain series resistance (R_sd) extraction method is not applicable to nanowire field effect transistors (NWFETs), as NWFETs have fluctuating characteristics in Id and there is insufficient physical modeling. In this letter, we propose a modified R_sd extraction method that uses an optimized Id equation and a threshold voltage (V_th) extraction procedure for NWFETs. The Id equation is modified for the geometry of the NWFET, and V_th is obtained from the linear Y-function that can be observed in NWFETs because of volume inversion. A necessary assumption for this procedure is experimentally confirmed using the Y-function, and equations that fit the measured data perform well; this justifies the validity of applying the modified Id equations to NWFETs. Therefore, R_sd is perfectly extracted in all NWFETs and it is observed to be dependent on the channel diameter (d_NW) when normalized by d_NW, indicating that the extension resistance is the dominant component in the total R_sd.