Superlattice-like Sb-Ge thin films for high thermal stability and low power phase change memory

The thermal properties of Sb-Ge superlattice-like thin films have been experimentally studied for phase change memory. The Sb-Ge superlattice-like thin films have a high crystallization temperature (223 °C). The interdiffusion coefficient Dλ was determined by measuring the intensity of the low-angle X-ray diffraction arising from the modulation as a function of annealing time. The temperature dependence in the temperature range 80-200 °C is described by Dλ = 8.3 × 10−24exp(-0.42 eV/kT) m2/s. The thermal stability of Sb-Ge superlattice-like thin films can also dramatically be improved with the increase of the temperature. The density variation of Sb-Ge superlattice-like thin films changes by only around 8% between amorphous and crystalline states, which is very important for device reliability. The threshold current and threshold voltage of a cell based on Sb-Ge are 8.15 μA, 1.07 V, respectively. The lower RESET power is presented in the PCM cells of Sb-Ge superlattice-like thin films, benefiting from its high resistivity.