Study of adhesion of TiN grown on a polymer substrate

TiN films were deposited on polycarbonate substrates by cathodic vacuum arc using the plasma immersion ion implantation and deposition (PIII&D) method. The biaxial intrinsic stress in the film deposited using PIII&D with 3 kV applied bias was 0.3 GPa — much lower than that found in films deposited without the application of high-voltage pulsed bias. It was found that the dominant mechanism for generating stress in the TiN film was thermal stress arising from the large difference between the thermal expansion coefficient of TiN and that of the polymer. Tensile testing was used to ascertain film adhesion and a model was used to estimate the adhesion between the film and the substrate. It was found that PIII&D strongly reduced the stress in the TiN film and increased the adhesion to the polycarbonate. The ultimate shear strength of adhesion is of the same order of magnitude as that of TiN on stainless steel.