Parasitic reset in the programming transient of PCMs

We studied the programming dynamics in phase change memory cells. It is shown that programming in stand-alone cells is strongly affected by the parasitic capacitance in the measurement setup, leading to a current overshoot after threshold switching of the amorphous chalcogenide. This results in a parasitic melting and quenching of the active material, affecting the current distribution during program and the final phase distribution in the active material. The relevance of this artefact for real-device operation is discussed with reference to the value of the parasitic capacitance.