Visualization of Conductive Filament during Write and Erase Cycles on Nanometer-Scale ReRAM Achieved by In-Situ TEM

The paper shows clear evidence that in-situ transmission electron microscopy (TEM) can be used as a powerful tool to analyze ReRAM operation. Reproducible resistive switching of 100k cycles in 30- or 70-nm Cu-Te CBRAMs was achieved for the first time during in-situ TEM observation. A TEM sample of the CBRAM cells was processed by a focused ion beam method. The formation and rupture of a Cu filament was observed and analyzed in the TEM with energy dispersive x-ray (EDX) mapping. Since the overshoot current at the resistive switching was efficiently suppressed by a MOSFET placed in the TEM holder, stable and reproducible ReRAM switching operations were achieved in the TEM.