Optimization Metrics for Phase Change Memory (PCM) Cell Architectures

In Phase Change Memory (PCM) the storage element can be realized with different cell architectures [1-4], involving two main device approaches to heat up and program the cell; those can be gathered together in the self-heating and in the heater-based families. Here we report on different PCM cell architectures, based on standard Ge2Sb2Te5 (GST) material, being fabricated with dedicated processes and studied in terms of their program/read efficiency and integration features. Despite the realized self-heating approaches showing slightly better efficiency, the heater-based Wall architecture is claimed to be the best one for process integration, still matching the electrical target. Further optimization guidelines for the Wall architecture, based on a simple model, are then provided, involving both electrical and thermal arguments.