Surface analysis studies of copper chemical vapor deposition from 1,5-cyclooctadiene-copper(l)-hexafluoroacetylacetonate

Abstract

The chemical vapor deposition of Cu from the 1,5-cyclooctadiene copper(I) hexafluoroacetylacetonate (COD-Cu-hfac) precursor has been studied using x-ray photoelectron spectroscopy, high-resolution electron energy-loss spectroscopy, and in situ reactor growth. Cu films are reproducibly grown on a Ag seed layer with resistivities of 2.0-2.4 μΩ cm with a deposition rate of 30–80 A/min at 180 °C. After deposition, the surface of the Cu is covered by some adsorbed precursor fragments and residual hydrocarbon. Upon heating in vacuum, the precursor desorbs leaving behind about 3–5 A carbon. Incorporation of carbon, oxygen, and fluorine into the bulk of the Cu films is limited to 1% or less. The reactive sticking coefficient of the COD-Cu-hfac molecule during deposition is estimated to be ~ 1 X 10“3 at 180°C. Cu grows somewhat selectively on metal relative to oxide surfaces at 180°C. Room temperature adsorption of the precursor on Ag leads to dissociation of the molecule and loss of the COD ligand. The stoichiometry of the surface complex corresponds to Cu(I)-hfac. Heating the surface to >170 °C leads to desorption of the surface hfac ligand. This is consistent with a bimolecular disproportionation reaction in which 2 Cu(I)-hfac species react to form a volatile Cu(hfac)2 complex and a reduced Cu atom. © 1992, American Vacuum Society. All rights reserved.