Embodiments of the present disclosure describe semiconductor devices with ruthenium phosphorus thin films and further describe the processes to deposit the thin films. The thin films may be deposited in a gate stack of a transistor device or in an interconnect structure. The processes to deposit the films may include chemical vapor deposition and may include ruthenium precursors. The precursors may contain phosphorus. A co-reactant may be used during deposition. A co-reactant may include a phosphorus based compound. A gate material may be deposited on the film in a gate stack. The ruthenium phosphorus film may be a metal diffusion barrier and an adhesion layer, and the film may be a work function metal for some embodiments. Other embodiments may be described and/or claimed.