Ultrathin (∼2nm) HfOx as the fundamental resistive switching element: Thickness scaling limit, stack engineering and 3D integration

This paper addresses the thickness scaling limit of HfO_x-based RRAM through a combination of theoretical calculations of electron transport and experimental demonstration of 2nm-HfO_x devices. The comparison of 2nm devices with thicker references and bilayer stacks confirm the switching thickness is less than 2nm. The 3D integration of 2nm-HfO_x devices enables much larger array size and leads to superior performances compared to planar devices.