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

Abstract

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 I-d and there is insufficient physical modeling. In this letter, we propose a modified R-sd extraction method that uses an optimized I-d equation and a threshold voltage (Vth) extraction procedure for NWFETs. The I-d equation is modified for the geometry of the NWFET, and Vth 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 I-d 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.