HOT-HOLE-INDUCED NEGATIVE OXIDE CHARGES IN N-MOSFETS

We investigate the generation of electron traps by hole injection duri ng hot-carrier stressing of n-MOSFET's. These generated electron traps are filled by an electron injection following the primary hole stress . The effect is proven and quantified by monitoring the detrapping kin etics in the multiplication factor and the charge pumping current. The traps are located in the oxide within the first few nanometers to the interface. An interaction of those traps with interface states is fou nd in that charged electron traps inhibit charging or uncharging of in terface states. The kinetics of hot-carrier-induced fixed negative cha rges in n- and p-channel MOSFET's are compared showing significant dif ferences in the properties of the two species of traps. Hole-induced e lectron traps are located much closer to the interface and their energ etic level is deeper. Finally, a method is presented that allows the q uantification of the effect for reliability purposes. We conclude that under digital and analog operation conditions in which hole effects c annot completely be ruled out, this effect has to be considered.