TDDB characterization of BST capacitors exhibiting bimodal Weibull distributions

BST thin-film capacitors breakdown have been studied as a function of applied voltage and temperature. This paper deals with a bimodal behaviour observed from Time Dependent Dielectric Breakdown (TDDB) experiments. This double population makes it difficult to assess properly the components reliability. We show that these two populations are related to two intrinsic and distinct failures. Through an extensive study of leakage current conduction mechanisms, we exhibit that the Poole-Frenkel model can be used for both populations with two distinct trap heights of 0.6 and 0.9 eV directly related to this reliability behaviour.