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 similar to 100 times and deposition is possible even at 50 degrees C with a rate of 250 Angstrom/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 mu m thick films with a root-mean-square roughness of 35 Angstrom. The electrical resistivity of the films is rho = 2 +/- 0.2 m Omega cm, close to the bulk value of 1.67 m Omega cm.