The effect of bias voltage on microstructure and hardness of TiN films grown by ion coating deposition

Titanium nitride (TiN) thin films were grown onto 316 stainless steel substrate at 350 degrees C by hollow cathode discharge ion plating technique. Since microstructure and mechanical properties of the samples were strongly affected by bias voltage, different bias voltages from 0 to | - 120| V were applied to the substrate. Rutherford back-scattering spectroscopy showed that the film thickness decreased when the bias voltage increased. X-ray diffraction patterns showed that the as-prepared TiN thin films were preferentially grown in the (200) direction with a satisfactory crystal quality at -30V. The spatial scaling behavior of the TiN films grown by ion coating have been investigated by using the atomic force microscopy as well as a kinetic roughening model for the film thickness ranging from 380 to 590 nm. The roughness and dynamic scaling exponents have been independently measured (alpha = 0.7 +/- 0.05 and z = 3.03 +/- 0.05) and they exhibited a smooth surface growth. Nanohardness showed formation of a film with 30 GPa hardness and 285 GPa Young modulus at -30V bias voltage.