A via failure mode in electromigration of multilevel interconnect

Via electromigration (EM) performance of (Al-1% Si-0.5% Cu)/(Ti/TiN/Al-1% Si-0.5% Cu) metallization systems has been evaluated for vias with sizes ranging from 1 mu m to 2 mu m. The electrical open failure mode for vias was observed during EM test at high temperatures and with different current densities. The activation energy and current exponent were obtained, suggesting surface and lattice diffusion as the probable failure mechanisms. A novel observation from this study was the self-healing of failed vias when the failed chains were stored at room or high temperatures. A model for the failure mechanism is proposed.<
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