Pseudo-breakdown events induced by biased-thermal-stressing of intra-level Cu interconnects-reliability and performance impact

The pseudo-breakdown (PBD) phenomenon has been investigated in intra-level reliability assessment of Cu-interconnects. Field and intralevel spacing dependence show that PBDs form an irreversible permanent damage path that differs from that of HBDs by the amount of Joule heat released via breakdown induced leakage path. An RC delay simulation demonstrates that PBD leakage may hinder the circuit performance with further device scale down. Physical failure analysis reveals the lower liner/IMD interface as the predominant leakage path accompanying PBDs, confirming the failure mechanism established through the local electric and stress field simulations. We propose a PBD induced leakage mechanism supported by experimental results.