Ta/Cu is a strategic material combination for ultra-large-scale integrated wafer technology. Here we report an unconventional method for the synthesis of a [110]-oriented nanocrystalline R-Ta thin film on freshly prepared Cu(111) templates at <50 °C without any redundant underlayers and post-growth treatments. The crystallite size of the R-Ta-containing thin film is in the range of only 6-8 nm, and the Ta film resistivity is reduced significantly from 186 µΩ cm down to 104 µΩ cm with this novel method.