Nanoscale filaments in Ta-O resistive RAM bit array: microscopy analysis and switching property

摘要

Ta-O-based resistive random access memory (ReRAM) cells arranged in one-transistor-one-resistor (1T1R) bit arrays were investigated using scanning transmission electron microscopy (STEM) in combination with energy dispersive X-ray spectroscopy (EDS). While conductive filaments (CFs) were less detected immediately after electroforming, they were observed with high probability after the number of memory operations exceeded 1 kilocycle (kc). The observed CFs were nm-scale and grew slightly with switching repetitions up to 100 kc. In addition to oxygen reduction, Ta accumulation was seen at the CFs. This phenomenon may become a source of future device degradation.