Detection of charge carrier confinement into mobile ionic defects in nanoporous dielectric films for advanced interconnects

Reliability and robustness of low-k materials for advanced interconnects has become one of the major challenges for the continuous down-scaling of silicon semiconductor devices. Metal catalyzed time dependent breakdown is a major force preventing integration of sub-32 nm process technology nodes. Here, the authors demonstrate that ions can behave as trapping points for charge carriers. A mechanism for describing trapping of charge carriers into mobile ions under bias and temperature stress is presented. Charge carrier confinement into ionic center was found to be dominated by ionic transport. After extended bias and temperature stress, the magnitude of charge trapping into ionic centers decreased. Simulations suggest that built-in fields could reduce the effect of externally applied fields in directing ionic drift, therefore inhibiting the trapping mechanism. This work depicts the dual role of ionic species when catalyzing dielectric failure (mobile defect and local field distortion).