The microstructural and electrical characterizations of RuxTa1-x alloys obtained from Ru-Ta laminates are presented. The films were deposited on SiO2 and HfO2 and capped with TiN to avoid oxidation of the top surface. The alloys were attained by post-anneal thermal treatments in the range of 500-1000 °C in Ar atmosphere. Co-sputtered RuxTa1-x alloys were used as references. In particular, Ru0.4Ta0.6 phase could be obtained when the Ru-Ta laminate was annealed at 1000 °C. The alloying reaction is limited either by the tantalum nitride or oxide formation being the source for Nitrogen the TiN capping used on top of the stack and the Oxygen either the dielectric films or the one stuffing the films after exposure to the atmosphere.
Independent of the Ta content a mid gap work function was obtained. Measured WF's in laminate-obtained alloys and alloys themselves differ from other literature data, where a more n-type like WF are measured, and indicating process dependence. In the present study mid-gap or rather p-type work functions were found, 4.5 eV < WF < 4.9 eV.