Barrier Integrity Effect on Leakage Mechanism and Dielectric Reliability of Copper/OSG Interconnects

摘要

In this paper, we investigate the effect of copper diffusion barrier integrity on the leakage behavior and dielectric reliability of copper/micro porous organo-silica-glass (OSG) interconnects. Significant differences in the field dependence of TDDB median-time-to-failure are observed when comparing sub-critical and sealing barriers. Also for the temperature acceleration of TDDB, a significant difference is found which is reflected in the thermal activation energies. With fast voltage ramp measurements, Ⅰ-Ⅴ curves of samples with sub-critical and sealing barriers are compared before and after constant current stresses. Above 1.4 MV/cm, the dominant leakage mechanism is found to be Frenkel-Poole emission regardless of barrier treatments and stress times. Below 1.4 MV/cm, however, the Ⅰ-Ⅴ characteristic is modulated by the barrier integrity, which can be attributed to copper diffusion into the inter-metal dielectric.