A New Method to Extract Carrier Velocity in Sub-0.1-$mu$m MOSFETs Using RF Measurements

A novel RF method based on the accurate extraction of the gate–source channel capacitance and intrinsic transconductance from measured
$S$
-parameters is proposed to determine the effective carrier velocity of sub-0.1-
$mu$
m MOSFETs in the velocity saturation region. This method is developed to avoid the errors associated with underestimated charge in traditional ones. Using the RF technique, the electron velocity overshoot exceeding the bulk saturation velocity is observed along with the linear dependence of measured electron velocity on
$1/L_ poly$
in bulk N-MOSFETs with a channel length of less than 0.085
$mu$
m. This extracted result is more accurate than that of previous methods, because
$v_ eff$
is directly determined from the gate–source channel capacitance at high V
$ ds$
instead of that at V
$ ds=0$
.