Deposition mechanism of MOCVD copper films in the presence of water vapor

The effect of water vapor on the initial nucleation and growth mechanisms of metallo-organic chemical vapor deposited (MOCVD) copper films from copper(II) hexafluoroacetylacetonate (Cu(hfac)(2)) on a pre-deposited Cr substrate has been investigated. A relatively low growth rate with a long incubation period was observed in the absence of water vapor. When an optimum water vapor flow rate was introduced into the system, enhanced growth rate was observed without degrading electrical properties of the copper film. However, XRD analysis of the initial deposited film revealed that the film mainly consisted of copper oxide (Cu(2)O), The oxygen in the copper oxide films deposited from Cu(hfac)(2) on pre-deposited Cr substrates is originated from the water vapor and not from the hfac ligand. Initial nucleation and growth of the deposited film is initiated by the reaction between the vapor phase precursor and water vapor forming copper oxide (Cu(2)O) at the surface and the oxide is then reduced to metallic copper by either a disproportionation reaction or by hydrogen molecules. The optimum water vapor flow rate is thus believed to be the driving force for the enhanced growth rate and a reduced nucleation delay without degrading the film resistivity. (C) 1998 Elsevier Science S.A. All rights reserved.