In a contact metallization employing Mo as a thin‐film ’’diffusion barrier’’, we have observed that this refractorymetal does not exhibit optimum barrier properties when rf sputtered in argon. It was found that the use of ∠1500 Å of rf‐sputtered Mo between Si and Au results in extensive Si and Au intermixing in <30 min at 450°C. Auger depth profile analysis confirmed that both Si and Au had moved through the Mo. This would preclude subsequent processing involving elevated temperature, as in a Silox deposition. The intermixing appears to proceed via a grain boundarydiffusion mechanism (E a =0.21 eV). Significant improvement in the intermixing time was obtained by the controlled incorporation of N2 into the Mo via reactive rf sputtering. A possible model for this improvement will be presented using the data obtained from microstructural analysis of the nitrided and unnitrided films.