Residual stresses are a major factor in the reliable operation of multi-layer thin film structures. These stresses may form due to defect incorporation during deposition, recrystallization, second-phase precipitation, thermal coefficient of expansion (TCE) mismatch, etc., as well as local plastic flow, delamination or cracking. In the literature, residual stresses are usually assumed to be constant in the plane of the film. This assumption is sometimes implicitly made, as in the cases where only two psi-tilts are used in the stress determination with the sin2Ψ analysis.
In this paper, we will review the possible causes of heterogeneous stress distributions in thin films and discuss their impact on x-ray stress determination techniques using some new data from W films.