The Degradation of Thin Silicon Dioxide Films Subjected to Pulse Voltage Stresses at Nanoscale

Abstract

In this paper, we report the observation of the degradation and breakdown of thin silicon dioxide films subjected to both the unipolar and bipolar pulse voltage stresses at nanoscale by using conductive atomic force microscopy. It is found that the unipolar pulse voltage stress produces more severe damage than does the bipolar pulse voltage stress. We also notice that hard breakdown is always preceded by soft breakdown for thin silicon dioxide subjected to either unipolar or bipolar pulse voltage stress, and the soft breakdown is always accompanied with random current fluctuation in the I-t characteristics. The influence of varying frequency of the pulse voltage stresses on the oxide breakdown is also investigated in this work.

Nanoscale Characterization of High-K/IL Gate Stack TDDB Distributions After High-Field Prestress Pulses

“…Moreover, one can see that the pre-stress leads to larger current fluctuations during the RVS than in the case without pre-stress. Similar observations have been made by [21] when studying the degradation of a SiO 2 film under a unipolar 10 kHz pulse voltage stress by C-AFM.…”

“…For this kind of pulse, IV characteristics do not present much differences compared to the ones obtained on unstressed oxide. However, a zoom on the current in the pA range reveals that the pre-stress induces a higher leakage current than in the case of the unstressed oxide as mentioned in [22], [21]. locations, which indicates that damages were created.…”