Endurance/Retention Trade Off in HfOx and TaOx Based RRAM

In this paper the memory performances of the TiN/HfO ₂ /Ti/TiN and TiN/Ta ₂ O ₅ /TaOx/TiN memory stacks are compared. First, the bipolar switching parameters and the effect of the compliance current on the memory window and endurance are investigated. Then, the endurance and data retention properties are compared at a given operating current (100μA). Ta ₂ O ₅ based memory stack exhibits a better memory window (2 decades) and data retention, while the HfO ₂ one shows good endurance properties (10 ⁸ cycles). Finally, thanks to ab initio calculations using Density Functional Theory, the stability of the conductive filament is investigated in both HfO _x and TaO _x dielectrics.