Internal stress in plasma polymer films prepared by cascade arc torch polymerization

Thin plasma polymer films were deposited from several liquid monomers (main ly siloxane-type monomers) in a low-temperature cascade are torch (CAT) rea ctor. The effects of monomer structures and plasma parameters on internal s tress in the films were experimentally studied. By appropriately adjusting these factors, the internal stress in the film was reduced nearly two order s of magnitude from 10(9) to 10(7) dyn/cm(2). It was noted that the polymer films prepared from siloxane-type monomers showed lower internal stress th an their hydrocarbon counterpart. Fourier transform-infrared spectroscopy ( FTIR) studies indicated that a large amount of Si-O-Si structure from silox ane monomers, which are very flexible bonds, was preserved in the resultant plasma polymers. Ellipsometry results suggested that the internal stress c an be qualitatively correlated with the refractive index of the plasma poly mer film. (C) 1999 John Wiley & Sons, Inc.