Effects of Ti Buffer Layer on Retention and Electrical Characteristics of Cu-Based Conductive-Bridge Random Access Memory (CBRAM)

We propose an ultrathin Ti buffer layer in the Cu/Al2O3 interface to overcome the high temperature retention failure and switching non-uniformity of conductive-bridge random access memory (CBRAM) device. The sacrificial effect of Ti resulted significant improvement in retention by minimizing Cu oxidization. A novel mechanism for this improvement on the basis of the difference in the electrode potentials of the Cu and Ti layers was also proposed. The Ti atoms help in retaining the copper filament with higher electrode potential by donating electrons to it. Moreover, device with a Ti buffer layer exhibits better uniformity that can be explained by the controlled diffusion of Cu ions through the buffer layer.