Communication: The deposition of smooth, dense, fine-grained, low resistivity copper films has been achieved at temperatures as low as 150-degrees-C from an organometallic precursor. It is suggested that the films (see figure) are formed as the result of thermal disproportionation of the precursor without decomposition of the ligand. Substrate-selective deposition at rates of over 1000 angstrom/min is demonstrated.