Ultra sharp Berkovich indenter used for nanoindentation studies of TiB2 thin films

TiB2 thin films (∼100 nm thick) were deposited on c-Si (1 0 0) wafers employing the d.c. unbalanced magnetron sputtering (UMS) technique. The influence of negative substrate bias Vb on the mechanical properties of TiB2 films was studied. Structural and morphological results were obtained by X-ray diffraction (XRD) and X-ray reflectivity (XRR) analysis whereas the mechanical properties were measured by means of depth sensing nanoindentation (NI). A detailed study of the influence of substrate mechanical properties on the measured elastic modulus (E) and hardness (H) was carried out using one sharp (BRK50) and one ultra sharp (BRK20) Berkovich type diamond tips with tip roundness 50 and 20 nm respectively. Bhattacharya–Nix (1988) [15] modified model was applied to assess thin film's intrinsic mechanical properties. Structural, morphological and mechanical testing results showed an improvement of mechanical properties of TiB2 thin films with the increase of the applied substrate bias voltage. Additionally they implied that BRK20 experimental results were less affected by substrate's mechanical properties.