Bilayer Metal-Oxide CBRAM Technology for Improved Window Margin and Reliability

In this paper, a detailed reliability analysis of metal-oxide CBRAM devices is presented. We demonstrated that the addition of a thin metal-oxide layer in the bottom of the memory stack significantly increases the ROFF and the memory window (more than 1 decade), with improved endurance performance. At the same time, high thermal stability was also achieved (window margin constant during more than 24 hours at 250°C). The origin of the window margin degradation during endurance is discussed and interpreted by means of a Trap Assisted Tunneling Model, putting in evidence the role of defect generation and Cu residual atoms in the resistive layer.