Comparative study of TiNx films deposited by reactive ion beam sputtering at 77 and 300 K

Comparative studies were performed on the chemical composition, the microstructure, residual stress, hardness and Young's modulus of titanium nitride films, which were prepared by reactive ion beam sputtering at substrate temperatures of 77 and 300 K. The main experimental parameter of sample preparation was the N2/Ar gas flow ratio r, which determines not only the chemical composition of the film, [N]/[Ti], but also its mechanical and electrical properties. The chemical composition was investigated by AES, XPS and RBS. Microstructural data were obtained by grazing incidence X-ray diffractometry. The measurements indicate a mixed phase of Ti, Ti2N and TiN at lower r ratios and of cubic TiN at r>0.05. From the integrated breadth of the diffraction lines, grain size D and strain e were determined: 150-250 A for D and 0.5-1.5% for e. The residual stress was measured by determining the bending of the substrate. Extraordinarily high compressive stress with pronounced maxima around stoichiometric composition was observed. The microhardness Hv and Young's modulus E were derived from the indentation loading-unloading curve, as measured with a nanoindenter. Values up to 25 GPa for Hv and up to 10 GPa for E were obtained. (author)