Study of the mechanical behavior of plasma-deposited silica films on polycarbonate and steel

In the present study, we deposited amorphous hydrogenated silicon oxide fil ms on polycarbonate, stainless steel, and silicon by plasma enhanced chemic al vapor deposition using a low pressure, high density integrated distribut ed electron cyclotron resonance plasma reactor. Substrate curvature, vibrat ing slab, and Vickers indentation experiments were used to evaluate the int rinsic stress, the Young modulus of the films, and the composite hardness o f the film-substrate system. The indentation experiments were modeled by fi nite element analysis and the calculated values were compared to experiment ally measured hardness values. A reasonable accordance with the experiment was found both for stainless-steel and polycarbonate substrates, indicating that the modeling is valid and may be used to enhance the interpretation o f the indentation experiments. The calculations show an important bending o f the film in the noncontact region in the case of a Vickers indentation on a coated polycarbonate sample. The analysis of the thus-induced strain dis tribution in the coating indicates that the measured diagonal might be over estimated and not representative of the real contact area. The calculations indicate that the yield limit of the plasma-deposited silica films is of a bout 4 GPa. (C) 2000 American Vacllnm Society. [S0734-2101(00)06604-5].