© 2015 Elsevier B.V. All rights reserved. The breakdown time statistics of successive failure events in constant voltage-stressed Al2O3/HfO2 nanolaminates grown by atomic layer deposition (ALD) is investigated. The oxide stack was deposited on a p-type Si substrate and Al was used as the top metal electrode. It is shown that the devices exhibit stepwise current-time characteristics which indicate the formation of multiple leakage current paths spanning the insulating film. It is demonstrated that the arrival rate of the breakdown events can be modeled as a combination of two power-law intensity functions within the framework of a nonhomogeneous Poisson process (NHPP). The change of trend observed during degradation is ascribed to the increasing role played by the series resistance effect in the voltage drop across the nanolaminate. A simple algorithm for calculating the arrival rate of the failure events based on a thinning method is discussed.
- Oxide breakdown
- Poisson process