Cu dual damascene interconnects in porous organosilica film with organic hard-mask and etch-stop layers for 70 nm-node ULSIs

Hybrid-type, Cu dual damascene interconnects (DDI) are fabricated in a porous organosilica film (k = 2.1) inserted between low-k films of hard-mask (HM) and etch-stop (ES) layers. Plasma-polymerized, divinyl siloxane bis-benzocyclobutene (p-BCB, k = 2.7) film, instead of SiCN film (k > 4), is selected for these HM and ES layers due to the low k-value as well as the high etch-stop property to the porous film. The line capacitance in the hybrid-type, Cu-DDI with BCB-HM and BCB-ES layers decreases 20% compared with that of the Cu-DDI with SiO₂-HM and SiCN-ES layers, achieving the effective dielectric constant (k_eff) of 2.6. This new interconnect structure is a strong candidate for the 70 nm-node ULSIs.