The behaviors of the substrate current and the impact ionization rate
are investigated for deep submicron devices in a wide temperature rang
e. New important features are shown for the variations of the maximum
substrate current as a function of applied biases and temperature. It
is found that the gate voltage V (g) (max), corresponding to the maxim
um impact ionization current conditions, is quasi-constant as a functi
on of the drain bias for sub-0.1 mu m MOSFET's in the room temperature
range. At low temperature, a substantial increase of V (g) (max), is
observed when the drain voltage is reduced. It is also shown that, alt
hough a significant enhancement of hot carrier effects is observed by
scaling down the devices, a strong reduction of the impact ionization
rate is obtained for sub-0.1 mu m M0SFET's operated at liquid nitrogen
temperature in the low drain voltage range.