Copper may become an alternative to aluminum as an interconnect material in ultralarge scale integration multilevel metallization schemes if it is possible to pattern Cu by dry etching in a manufacturable process. Here we report results on the reactive ion etching of Cu in SiCl4/Ar and SiCl4/N2plasmas. Etching has been investigated as a function of gas composition, pressure, and substrate temperature. We have obtained etch rates as high as 850 A˚/min using SiCl4/N2and a substrate temperature of ∼ 220 °C, with excellent etch selectivity of Cu relative to polyimide and SiO2. We demonstrate that it is feasible to pattern Cu anisotropically using polyimide as a high‐temperature etch mask.