Electric-field and temperature dependencies of TDDB degradation in Cu/Low-K damascene structures

Abstract

The electric field and temperature dependencies of time-dependent dielectric breakdown (TDDB) degradation in Cu/low-k damascene structures are investigated using Cu/SiOC and Cu/SiCN damascene structures. A field-dependent activation energy analysis of TDDB lifetimes demonstrates that there are multiple TDDB degradation mechanisms for a Cu/SiOC structure and that the dominant TDDB degradation mechanism is dependent on the electric field. Under higher electric fields, the SiCN film used as a Cu barrier dielectric (BD) is the main cause of the TDDB failure. As the electric field decreases, the degradation of the inter-level dielectric (ILD) or ILD/BD interface has an impact on TDDB failure. Furthermore, it was found that the field-dependency of Ea reflects the dominant TDDB degradation mechanism and is an important factor in determining a TDDB degradation model that can predict an accurate TDDB lifetime.