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Abstract:
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In this work, a new probabilistic model is developed for the breakdown lifetime of high-k gate dielectrics of a semiconductor under unipolar AC voltage stress. Assuming that the gate oxide layer is composed of a large number of potential breakdown cells, this model is derived based on the finite weakest-link model with a load sharing characteristic. Each potential breakdown cell is modeled as a series coupling of several sub-cells, which is analogous to the fiber bundle model for the strength statistics of material/structures. As in the previous engineering studies in this regard, the new model also shows that the dependence of the mean time to failure on the gate area deviates from the classical Weibull scaling law. Most importantly, it is demonstrated that the newly proposed model agrees better with the observed lifetimes of HfO2-based gate dielectrics under unipolar AC voltage stress, providing a new insight into the failure process of a high-k gate dielectrics in the risk management perspectives.
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