Spatio-Temporal Defect Generation Process in Irradiated HfO2 MOS Stacks: Correlated Versus Uncorrelated Mechanisms

In this paper, we analyze the dependence of the Weibull slope (ß) extracted from TDDB tests on HfO2 MOS capacitors (MOSCAPs) on the initial density of defects artificially induced by carefully tuned micro beam irradiation experiments with different carbon dosages. The consistent experimental trend of reducing $p$ with increasing defect density was reproducible only with physics-based breakdown simulations that considered correlated defect generation in HfO2 and localized damage (partial percolation paths) traces created by the impinging ions. Scenarios of spatially random initial defect distribution and random stress-induced defect generation (in space and time) could not explain the experimental trends, confirming that correlated defect generation does exist in HfO2 thereby altering the conventional understanding of TDDB by quite a bit.