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

The conventional source/drain series resistance
$(R_{\rm sd})$
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
$R_{\rm sd}$
extraction method that uses an optimized
$I_{d}$
equation and a threshold voltage
$(V_{\rm th})$
extraction procedure for NWFETs. The
$I_{d}$
equation is modified for the geometry of the NWFET, and
$V_{\rm th}$
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
$I_{d}$
equations to NWFETs. Therefore,
$R_{\rm sd}$
is perfectly extracted in all NWFETs and it is observed to be dependent on the channel diameter
$(d_{\rm NW})$
when normalized by
$d_{\rm NW}$
, indicating that the extension resistance is the dominant component in the total
$R_{\rm sd}$
.