Chemical Aspects of Reactive Metal and Energetic Ion Interactions on Polyimide

X-ray photoemission and in situ oxygen uptake studies have been performed on polyimide surfaces exposed to controlled ion etching, reactive metallization, or the two acting in concert. Although the ion etching process utilized in the current study was highly destructive in terms of bond scission and was found to exhibit enhanced selectivity for the removal of carbonyl oxygen atoms, the resulting surface was not observed to be reactive to a subsequent in situ oxygen exposure. This observation suggests that the bond cleavage induced by energetic ions does not produce a surface containing significant densities of stable organic radicals but, rather, results in the extensive cross-linking of the surface with the concomitant formation of highly unsaturated or graphitelike residues. Exposure of an unsputtered polyimide surface to Al deposited under UHV conditions results in the reduction of surface carbonyl functional groups. We conclude, based on subsequent oxygen titration data, that there is little evidence for significant metal-carbon bond formation. Aluminum deposited on a sputtered polyimide surface shows little evidence for charge transfer between the metal and the carbonaceous, surface residue.