RESIDUAL-STRESS DETERMINATION BY X-RAY-DIFFRACTION IN TUNGSTEN THIN-FILMS

In this study, the complete residual stress tensor has been determined by X-ray diffraction, using the sin2psi method, in 1000 and 2500 angstrom tungsten thin films deposited by ion beam sputtering on a silicon monocrystal. In the first case, we found very high tension stresses (about 1.5 GPa) for the as-prepared state and important compressive stresses (about -1.3 GPa) after an implantation with a dose of 10(16) Xe2+ ions/cm2 at 320 keV. In the second case, the film was almost detached from its substrate and the stresses were compressive (about -0.9 GPa). In all cases, the free-stress lattice parameter was different from the bulk one, indicating significant differences between the microstructure of these thin tungsten films and the one of the bulk. The size of the coherent domains of diffraction was also determined and was found to largely vary from one case to the other.