Barrier-metal-free (BMF), Cu dual-damascene interconnects with Cu-epi-contacts buried in anti-diffusive, low-k organic film

Abstract

Barrier-metal-free (BMF) Cu dual-damascene interconnects (DDI) are fabricated in the plasma-polymerized, divinyl siloxane bis-benzocyclobutene (p-BCB: k=2.6) polymer film, which is characterised by anti-diffusive characteristics for the Cu. The BMF-structure has inter-line leakage current as low as that of a conventional barrier-inserted structure and is estimated to retain the high insulating properties for over 10 years under 1 MV/cm stress. The BMF-structure also derives Cu-epi-contacts, reducing the via-resistance to 50% of that of the conventional Cu/barrier/Cu contacts. The effective dielectric constant was k/sub eff/=3.1, including very thin SiN etch-stop-layers, accomplishing 20% faster CMOS device operation compared to that of the conventional Cu-DDI in the SiO/sub 2/ with Ta-TaN barriers. The BMF Cu-DDIs buried directly in the p-BCB film is one of the ultimate structures for high performance, 0.1 /spl mu/m-CMOS devices and beyond.