Reduction of resistivity in Cu thin films by partial oxidation: Microstructural mechanisms

The microstructure and electrical resistance of sputter deposited copper thin films grown in an oxygen containing ion-beam sputtering atmosphere are discussed. For thicker films, there is a monotonic increase in resistivity while for films thinner than 5 nm, 6%-10% oxygen causes a minimum in film resistivity. Smoother films for these oxygen flow rate are shown by X-ray reflectivity measurements. The results of X-ray diffraction show that the oxygen doping causes the formation of cuprous oxide and a refinement of the copper grain size.