Impact of process variability on BEOL TDDB lifetime model assessment

We investigate the impact of process variability on BEOL TDDB lifetime model assessment. The change in functional form of TDDB lifetime plots due to line-to-line variability and line-edge-roughness has been quantified in the field range in which long term TDDB measurements have been obtained. We found that the Pearson R-2, which is used as a measure of linearity of a lifetime plot, did not significantly change due to process variability. Where process variability has a significant effect on TDDB and needs to be taken into account during data analysis, our simulations suggest that it does not have an impact on BEOL TDDB lifetime model assessment. We propose that the conclusions from recent literature reports which point in the direction of a less conservative model compared to the E-model are valid, although they do not take process variability into account during the data analysis.