The effect of substrate temperature and biasing on the mechanical properties and structure of sputtered titanium nitride thin films

The mechanical properties of titanium nitride (TiNx) thin films have been investigated using depth sensing nanoindentation tests. The effects of substrate temperature (Ts) and of substrate biasing (Vb) on the mechanical properties and the microstructure of the TiNx films were studied. Ts and Vb have strong effect on the filmʹs microstructural characteristics such as density, grain size and orientation. It was found that deposition at high Ts and Vb promotes the growth of (002) oriented films with density close to the bulk density of stoichiometric TiN, indicating the absence of voids and the growth of stoichiometric TiN. The film hardness and elastic modulus were measured using the continuous stiffness measurements technique. It was found that there exists a direct correlation between the filmʹs mechanical properties and microstructure. The films that exhibit the best mechanical performance are those grown along the (002) orientation and being denser and stoichiometric.