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

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 Å/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 Å 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 × 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.