Initial leakage current related to extrinsic breakdown in HfO2/Al2O3 nanolaminate ALD dielectrics

Multiple successive breakdown events are reported for HfO2/Al2O3 nanolaminate dielectrics grown by atomic-layer deposition. The first breakdown distribution is not a Weibull distribution and shows a long TBD tail at high failure percentiles. Analysis of the correlation between time-to-breakdown and initial current leakage allows identifying this tail with extrinsic breakdown. Screening of the data to eliminate the extrinsic tail demonstrates that the successive breakdown events are completely uncorrelated and perfectly match the successive breakdown theory. The statistical correlation between initial current and extrinsic breakdown distribution is explained in terms of variations of the unintentional interfacial SiOx layer at the silicon substrate/dielectric interface.

Multiple successive breakdown events are reported for HfO2/Al2O3 nanolaminate dielectrics grown by atomic-layer deposition. The first breakdown distribution is not a Weibull distribution and shows a long TBD tail at high failure percentiles. Analysis of the correlation between time-to-breakdown and initial current leakage allows identifying this tail with extrinsic breakdown. Screening of the data to eliminate the extrinsic tail demonstrates that the successive breakdown events are completely uncorrelated and perfectly match the successive breakdown theory. The statistical correlation between initial current and extrinsic breakdown distribution is explained in terms of variations of the unintentional interfacial SiOx layer at the silicon substrate/dielectric interface.Figure optionsDownload as PowerPoint slideHighlights
► Multiple breakdown events are measured in Al2O3 films and Al2O3/HfO2 nanolaminates.
► Initial leakage current distribution reveals existence of defective samples.
► Initial current distribution and extrinsic breakdown are related.
► Measuring initial current can make product reliability assessment more efficient.