Operating-Current Dependence of the Cu-Mobility Requirements in Oxide-Based Conductive-Bridge RAM

In this letter, we compare the switching performances of Cu-based CBRAM cells having either Al₂O₃ or SiO₂ dielectric layer. Both electrical and physical characterizations revealed different Cu mobility in the two dielectrics, impacting forming/switching speed and variability as well as functionality at low current. The modeling of the conduction also indicated different filament shapes in the two dielectrics. Based on the results, dielectrics allowing high Cu mobility are required when filament temperature is low, i.e., for low-current application (<;10 μA), while dielectrics allowing moderate Cu mobility are more appropriate for higher current ranges (≥10 μA), whereby Cu mobility is highly assisted by temperature.