Heterogeneous nucleus-induced crystallization for high-speed phase change memory applications

Abstract

Phase change memory has high potential for next-generation nonvolatile memory technology. The effect of lower layer Sb2Te (ST) on the crystallization process of Ge2Sb2Te5 (GST) is investigated by observing the change of the microstructure. Compared to the GST-based device, this paper achieved a faster operation speed (20 ns) with stable SET and RESET resistances via the addition of ST under the GST. The crystallization of lower layer ST occurs prior to that in the upper layer GST due to lower crystallization temperature, and the crystal grains of ST can supply the heterogeneous nuclei to reduce the nucleation time and enhance the crystallization speed of GST, which accounts for the improved operation speed. In addition, the effect of atomic migration on the GST/ST interface and the device performance is also investigated.