Methodology for the characterization and observation of filamentary spots in HfO_x-based memristor devices

摘要

Filamentary TiN/Ti/HfO2/W resistive switching devices were fabricated and electrically measured setting them in different resistance and degradation conditions. The TiN/Ti top electrode layer was then chemically removed by specifically selected reagents for the materials of these devices. This methodology caused the formation of plate-shaped microstructures in the W bottom metal layer. However, the HfO2 dielectric layer was not affected due to the selectivity of the etchants. Filamentary structures in the insulator layer of the devices were found in the center of these "microplates". The top morphology and the size of the filaments were characterized by physical inspection techniques. The analysis of the results highlighted the correlation between the device electrical degradation, the resistance state and the physical nature of the filamentary path.