Degradation of the Reset Switching During Endurance Testing of a Phase-Change Line Cell

In this brief, we studied the endurance properties of an integrated phase-change line cell. The different characteristics typically observed during the endurance lifetime are described. The monitoring of the switching parameters of the cell (reset current and threshold voltage) during endurance testing could be correlated with a gradual degradation of the reset switching. The following conclusions were drawn: 1) The reset-switching degradation is closely associated to both an increase of the minimum reset current and a decrease of the obtained reset and set resistances, pointing to material change; 2) the extent of the degradation strongly depends on the reset pulsewidth, and it was found to scale with tm ^3/2, tm being the melting time during reset pulse; however, higher reset currents did not quicken the onset of degradation; and 3) the tm ^3/2 dependence together with polarity-dependent endurance tests suggests the contribution of an electrical-field-driven migration mechanism. Based on these insights, the extended endurance lifetime of more than 10¹⁰ cycles could be demonstrated, using short reset pulses, which could be further increased by changing reset polarity before stuck-set failure.