Degradation of Short-Channel MOS Transistors Stressed at Low Temperature

Hot-carrier stressing was carried out on 1 ¿m n-type MOSFETs at 77 K with fixed drain voltage Vd = 5.5 V and gate voltage Vg varying from 1.5 to 6.5 V. It was found that the maximum transconductance degradation and threshold voltage shift do not occur at the same Vg. This behavior is explained by the localized nature of induced defects which is also responsible for a distortion of the transconductance curves and oven a slight temporary increase in the transconductance during stress. An anomalous increase in the saturation transconductance is also reported.