Condensation coefficients and initial stages of growth for noble metals deposited onto chemically different polymer surfaces

The initial stages of growth of noble metals deposited onto untreated as well as Ar+ beam-treated polymer surfaces were investigated by means of X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and radiotracer methods. Condensation coefficients C of the metals on the polymer surfaces were determined by comparison of the XPS signals of the metals with the nominal thicknesses measured by a quartz microbalance during deposition. These measurements were combined with radiotracer measurements, which allow to determine C independently with high accuracy and sensitivity. C was found to depend strongly on the chemical composition of the polymer surface, e.g., at room temperature, C varies between 0.95 for PMDA-ODA polyimide and 0.002 for Teflon AF. By ion beam treatment of the latter, C was raised considerably. During nucleation of the metal on the polymer surface, C increases strongly with metal coverage. C also depends on the deposition rate of the metal and decreases strongly at elevated temperatures. (C) 1999 Elsevier Science B.V. All rights reserved.