Leakage current distribution in ultrathin oxide on silicon surface with step/terrace structures

Leakage current distribution in ultrathin SiO₂ film formed on (111) Si surface with step/terrace structures was investigated using atomic force microscopy with a conductive cantilever. Regions with higher leakage current of 1.0-nm-thick SiO₂ were observed in line along the atomic steps. In a case of 1.4-nm-thick SiO₂, even if a relationship between the leakage current distribution and the atomic step positions is not observed at the initial stage, the high voltage stress application makes the relationship clear. The atomic step edges have a great influence on their initial leakage and the reliability of the ultrathin oxide.