Switching Power Reduction in Phase Change Memory Cell Using CVD Ge[sub 2]Sb[sub 2]Te[sub 5] and Ultrathin TiO[sub 2] Films

Abstract

Phase change memory cells were fabricated using plasma-enhanced cyclic chemical-vapor-deposited Ge 2 Sb 2 Te 5 (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 TiO 2 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) TiO 2 layer decreased the necessary reset power to ∼45% of the cell without the TiO 2 layer. This was attributed mainly to the effective heat insulation by the 4 nm thick TiO 2 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 TiO 2 layer interposed cell. © 2008 The Electrochemical Society.