One important issue for integrating atomic layer deposition (ALD) TaN on a template type porous low-k film is penetration of Ta precursor into the pores, Deposition of a thin film on a patterned sidewall by plasma enhanced chemical vapor deposition (PECVD) is a candidate for pore sealing. We have examined PECVD-SiCH from tetramethylsilane (Si(CH3)(4):4MS] as a pore sealant and compared it to PECVD-SiOC from 4MS/CO2 and SiO2 from tetraethoxysilane [Si(OC2H5)(4):TEOS]. ALD-TaN had an incubation time on a blanket SiCH, while it did not on a SiCH patterned wafer. The SiCH had the lowest deposition rate and the highest step coverage which enabled deposition of an ultrathin pore-sealing film as thin as 2 nm, Damascene Cu interconnects fabricated by using ALD-TAN barrier metal and the ultrathin SiCH pore-seal demonstrated good electrical characteristics which successfully presented the increase in leakage current due to metal penetration, and it minimized the increase in line resistance by keeping the sealing layer thin. (c) 2005 American Vacuum Society.