Surfactant-Catalyzed Chemical Vapor Deposition of Copper Thin Films

A novel concept of chemical vapor deposition that uses a simple atomic adsorbate as a catalytic surfactant is introduced and demonstrated for deposition of copper thin films from Cu I (hfac)(vtms). A submonolayer of iodine atoms adsorbed on the copper film surface catalyzes the surface reaction to reduce the activation energy from 15.3 kcal/mol for the uncatalyzed deposition to 6.1 kcal/mol. As a result, the growth rate is enhanced by as much as ∼100 times and deposition is possible even at 50 °C with a rate of 250 Å/min. The product analysis by gas chromatography−mass spectroscopy reveals that on an I-adsorbed surface Cu I (hfac) ad further dissociates into Cu and (hfac) ad by interacting with an I ad atom, and (hfac) ad subsequently recombines to desorb as (hfac) 2 . For the uncatalyzed deposition, the disproportionation reaction between two [Cu I (hfac)] ad complexes was confirmed. Iodine adatoms also act as a segregating surfactant to suppress the surface roughness, allowing deposition of 1 μm thick films with a root-mean-square roughness of 35 Å. The electrical resistivity of the films is ρ = 2 ± 0.2 mΩ cm, close to the bulk value of 1.67 mΩ cm.