Nano-analytical investigation of the forming process in an HfO2-based resistive switching memory.

Metal oxide-based resistive random access memory devices are highly attractive candidates for next-generation nonvolatile memories, but the resistive switching phenomena remain poorly understood. This article focuses on the microscopic understanding of the initial forming step, which is decisive for the switching process. The integrated resistive switching memory effect in Ti / Hf O 2 / TiWN metal insulator metal structures is studied. After forming, transmission electron microscopy investigations pointed out the presence of a funnel-shaped region, in the ON state of the cell, where slightly oxidized Ti (Ti Ox ) was present within Hf O 2 dielectric. Modeling of the measured ON state conductance of the cell with the semi-classical approximation is consistent with a conductive nanometric Ti Ox filament (or a sum of sub-nanometric Ti Ox filaments) present in the funnel-shaped region. The conductive area is likely formed by diffusion after the dielectric breakdown. [ABSTRACT FROM AUTHOR]