Electrical characterization of the soft breakdown failure mode in MgO layers

The soft breakdown (SBD) failure mode in 20 nm thick MgO dielectric layers grown on Si substrates was investigated. We show that during a constant voltage stress, charge trapping and progressive breakdown coexist, and that the degradation dynamics is captured by a power-law time dependence. We also show that the SBD current-voltage (I-^V) characteristics follow the power-law model I=a V^b typical of this conduction mechanism but in a wider voltage window than the one reported in the past for SiO₂. The relationship between the magnitude of the current and the normalized differential conductance was analyzed.