Switching power reduction in phase change memory cell using CVD Ge ₂Sb₂Te₅ and ultrathin TiO₂ films

Phase change memory cells were fabricated using plasma-enhanced cyclic chemical-vapor-deposited Ge₂Sb₂Te₅ (GST) thin films deposited on 300 nm diameter TiNW contact plugs formed in a SiO ₂ layer. A 2, 4, and 8 nm thick atomic deposited TiO₂ layer was interposed between the GST and underlayer containing the contact plug. The necessary reset current and power decreased with increasing the TiO ₂ interlayer thickness. Adoption of the optimum thickness (4 nm) TiO₂ layer decreased the necessary reset power to ∼45% of the cell without the TiO₂ layer. This was attributed mainly to the effective heat insulation by the 4 nm thick TiO₂ layer. The structural investigation and electrothermal simulation results for the fabricated cells showed a good match between the electrical performance and phase changed volume, which can explain the improvement in switching parameters of the proper TiO₂ layer interposed cell.