In this study, intralevel dielectric breakdown is studied for copper interconnects in an SiOF dielectric, capped with either SiN or SiCN. The leakage current is higher and the failure time of dielectric breakdown is shorter for an SiCN capping layer compared to an SiN capping layer. It is proposed that the dielectric breakdown of the integrated structure is limited by the interface between the capping layer and the SiOF dielectric. Lower lifetime for dielectric breakdown is observed for structures with an SiCN cap compared to structures with an SiN cap, due to higher leakage current in the SiCN. The higher leakage for an SiCN cap is consistent with results from planar metal-insulator-semiconductor capacitors.