10×10nm<sup>2</sup> Hf/HfO<inf>x</inf> crossbar resistive RAM with excellent performance, reliability and low-energy operation

Abstract

We report on world's smallest HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based Resistive RAM (RRAM) cell to date, featuring a novel Hf/HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> resistive element stack, with an area of less than 10×10 nm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , fast ns-range on/off switching times at low-voltages and with a switching energy per bit of <;0.1pJ. With excellent endurance of more than 5.10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> cycles, large on/off verified-window (>;50), no closure of the on/off window after 30hrs/200C and failure-free device operation after 30hrs/250C thermal stress, the major device-level nonvolatile memory requirements are met. Furthermore, we clarify the impact of film crystallinity on cell operation from a scalability viewpoint, the role of the cap layer and bring insight into the switching mechanisms.