A Novel Programming Method to Refresh a Long-Cycled Phase Change Memory Cell

Degradation of device characteristics as a presage of the 'stuck to SET' failure of a long-cycled phase change memory device was investigated to illuminate its cause and to propose a novel programming method that can cure the problem for an extended device life time. From the finding that the degraded RESET characteristics could be cured by reverse RESET current pulses, field-induced atomic migration was confirmed to play a determining role. It was vividly demonstrated that life time of a phase change memory device could be greatly extended by periodically imposing reverse RESET current pulses during normal operations.