Resistive random access memory (ReRAM) is one of the candidates to alternate NAND flash memory due to its potential scalability, fast switching speed and low operating power [1]. However, for ReRAM in general, high-voltage forming process is needed to initiate the switching, which normally lead to high power consumption and operational complexity [2]. Therefore, the forming-free operation of ReRAM has been researched globally. In this work, to overcome this high voltage forming operation, the effect of Cu-doping on switching layer of amorphous carbon-oxide ReRAM was studied. ReRAM was fabricated with the structure of tungsten (W) / Cu-doped amorphous carbon oxide / hafnium oxide (HfO₂) / platinum (Pt). The buffer layer, hafnium oxide, was inserted to decrease the current level increased excessively due to Cu-doping. It was confirmed that Cu-doping decreased forming voltage and increased memory margin. As comparing the characteristics of the ReRAM with and without Cu-doping at 34-nm pattern size, the forming voltage of Cu-doped ReRAM decreased from 2.7 to 1.95 V and also set voltage of that decreased a little from 1.8 to 1.65 V. From I-V characteristic graph, Cu-doped ReRAM demonstrated that the forming voltage was similar to the set voltage, indicating for the possibility of forming free operation. In addition, the memory margin of that was enlarged from 1.62×10² to 2.64×10³. Besides, both of the devices had 10⁶AC endurance cycles, which were excellent performance compared with other ReRAM devices. In our presentation, we report the effect of Cu-doping on electrical characteristics and the switching mechanism by using various analysis tools such as transmission electron microscopy (TEM).

* This material is based upon work supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) under Industrial Technology Innovation Program (10068055).

[1] Li Ji; Integrated one diode-one resister architecture in nanopillar SiO_xresistive switching memory by nanosphere lithography. Nano Lett. 2014, 14, 813-818

[2] Ruomeng Huang; Forming-free resistive switching of tunable ZnO films grown by atomic layer deposition. Microelectron. Eng. 2016, 161, 7-12