Nitridation of TiSi2 has been shown to provide a self‐aligned diffusion barrier layer on top of the silicide. A detailed analysis of the nitridation mechanism shows that the compound formed is TiN as commonly expected. The reaction TiSi2→TiN starts at the surface and progresses through the silicide film with a laterally uniform interface. The Si atoms that are dissociated from the TiSi2 grow epitaxially onto the Si substrate material. Implications for contact applications are mentioned.