3D characterization of hard breakdown in RRAM device

Resistive Random Access Memory (RRAM) device is considered as a promising NVM device to replace flash memory device due to its simple design, small size and low operating conditions. The reliability of RRAM devices has been studied with respect to endurance, retention and variability for many years. However, the increasing demand of high performance and drastic down scaling trend make the reliability issues more challenging than before. In this work, a comprehensive study of hard breakdown (HBD) process in crossbar RRAM device was carried out via electrical, compositional and structural characterization methods. The results confirm that the HBD process was caused by Ta2O5 dielectric breakdown with intensive joule heating and melting process. The 3D structures of defects are well reconstructed. The percolation path was confirmed to be located at the edges of crossbar structure due to the low quality of peripheral materials and process variation. The presented work can offer a critical insight on preventing the HBD process in crossbar RRAM structure.