In [50] the effect of the T-gate head shape above the
gate foot on the capacitances was demonstrated, which has a
similar impact as the gate length
at the gate foot itself.
Thus, the shape of the gate head statistically influences the
device as much as the statistical gate length variations.
For the ohmic contacts a statistical variation is introduced by the alloying depth and
actual contact geometry of the contacts. For the semiconductor line resistance indirectly the
SiN/barrier interface influences the average mobility as the surface potential leads to a
partially depleted barrier layer. Variations of geometry or even slight changes of the surface
potential due to process induced remaining surface pollution will thus affect the current path and
the average mobility leading to effective changes of the parasitic resistances
and
.