The feasibility of etching Cu/low-k interconnects by using a low global warming potential CF3I plasma was studied. Low-damage etching was done and porous SiOC (p-SiOC, k < 2.6) film with low roughness was produced. Exposing p-SiOC film to CF3I plasma was found to suppress the decrease in the CH3 group and the increase in the k value compared to those of conventional CF4 and C4F6 plasmas. These effects are due to the low UV intensity and small amount of F radicals of CF3I plasma. The authors also found that the etching profile of CF3I plasma was comparable with that of CF4 plasma. Since the etching selectivity (p-SiOC/ArF photoresist) of CF3I plasma is higher than that of CF4 plasma, the remaining photoresist thickness increases after etching, thus suppressing line edge roughness (LER). The decreased LER mitigated degradation of IV and time dependent dielectric breakdown characteristics in Cu interconnects. They also found that the roughness on the bottom surface of the p-SiOC trench was reduced. These benefits are due to CF3I plasma's low reactivity with the carbon in photoresists and p-SiOC films. Based on these findings, they believe that the environmentally friendly CF3I gas has great promise as a p-SiOC etching material. (C) 2008 American Vacuum Society.