Behavior of SiO2 Under High Electric Field/Current Stress Conditions

Various results reported to-date by several investigators tend to give conflicting conclusions regarding the mechanism of dielectric degradation due to high electric fields. We have investigated the reasons for these differences and from this work have proposed a more unified model. We have found that as the electric field is increased first positive charges are created causing negative Vt shift. With higher E-fields a reversal in polarity of net charges was observed. Just prior to breakdown, the creation of electron traps was also accompanied by severe degradation in transconductance. This later degradation is due to interface damage giving rise to surface states. This degradation has the most detrimental effect on the dielectric life time. The effect of other levels of E-field/current injection stressing on life time is also investigated.