Abstract The impact of barrier metal on electrical performance of Cu/low K (Black Diamond™) in 0.13-μm dual damascene (DD) interconnection has been investigated. The via resistance and its distribution were reduced by using high-density plasma barrier metal (Ta) deposition technique. The average breakdown electrical field for samples with high-density plasma barrier metal (Ta) was increased to 2.4 MV/cm as compared to samples with conventional Ta deposition. Transmission electron microscope (TEM) images reveal that nonuniformity of barrier metal on the sidewall and bottom of the DD structure were significantly improved by applying high-density plasma barrier metal (Ta) deposition technique. Burn-in test at 200 °C for 1000 h was carried out, and it was found that there was no significant change of via resistance and line–line leakage behavior. The thickness of barrier metal was also optimized. Electrical results show that high-density plasma barrier metal deposition of 200 A Ta improved electrical performance and enhanced the reliability of 0.13-μm dual damascene interconnection.