SiO2dielectric breakdown mechanism studied by the post-breakdown resistance statistics

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Abstract
The dielectric breakdown mechanism of ultra-thin SiO2 is discussed on the basis of the experimental results of the post-breakdown resistance (Rbd) distribution. We have noticed that the Rbd of SiO2 in MOS devices is strongly related to the SiO2 breakdown characteristics such as the polarity dependence, the oxide field dependence or the oxidation process dependence of Qbd. In this paper, we discuss the dielectric breakdown mechanism of SiO2 from the viewpoint of the statistical correlation between the Rbd distribution, the Qbd distribution and the discharging energy at the SiO2 breakdown, by changing the stress polarity, the stress field, the oxide thickness and the oxidation process. In the case of hard breakdown, it has been clarified that the Rbd distribution for substrate electron injection is clearly different from that for gate electron injection. We have also found that, irrespective of the stress current density, the gate oxide thickness, the stressing polarity and the oxidation process, Rbd can be uniquely correlated to the discharging energy at dielectric breakdown, in the case of hard breakdown. Furthermore, it has been clarified that the Rbd does not depend on the energy dissipation at soft breakdown.