Residual stress depth profiling based on a triaxial stress model: the principal stress gradients in magnetron-sputtered molybdenum films

Asymmetric X-ray diffraction was used to study the gradients within a triaxial principal residual stress state in a 1.0 mu m magnetron-sputtered molybdenum coating. The depth information was investigated by varying the angle of incidence alpha and the resulting alteration in the X-ray penetration depth. The evaluation method used, which is based on pattern decomposition, extracts all sample-specific contributions (reflection broadening, 2 theta shifts) from the diffractograms and considers the diffraction geometry characteristic aberrations. This procedure allows the depth profiles of all principal stress components to be resolved. The in-plane stresses sigma(11) and sigma(22) show a progression of compressive stresses in the direction towards the substrate interface. The resolution of the depth profile of the z component sigma(33) was also successful, indicating a steep gradient in tensile stress in the near-surface region.