Effect of metal buffer layer and thermal annealing on HfOx-based ReRAMs

In this paper, we investigate different methods and approaches in order to improve the electrical characteristics of Pt/HfOx/TiN ReRAM devices. We discuss the improvement of the ReRAM electrical characteristics after the insertion of a Hf and Ti buffer layer. As a result, the resistance window increases more that 10 times, and the set and reset voltages decrease both in absolute value and variability. Furthermore, we show the influence of an annealing step at different temperatures on the Pt/HfOx/Hf/TiN memory devices on forming voltage and HRS. Considering the importance of achieving high density memory, we demonstrated the possibility of multi-level resistance state in the fabricated devices bu controlling the enforced compliance current. In addition, we show the endurance characteristic of the fabricated memories and their error rate. Finally, we report the transient behavior of the memory devices, investigating the device speed and switching mechanism.