The effects of vacuum annealing on the film properties of titanium boride (TIB_x) grown on (100)Si substrate

In order to investigate the effects of vacuum annealing on the properties of titanium boride films (TiB_x) on a (100)Si substrate, TiB_x/Si samples were prepared by the co-evaporation process and then annealed in the temperature range of 300-1000°C. The interfacial reaction of TiB_x/Si systems and the thermal stability of non-stoichiometric TiB_x films (0≤B/Ti≤2.5) were investigated by means of sheet resistance, x-ray diffraction, transmission electron microscopy, x-ray photo-electron spectroscopy, and stress measurement. For TiB_x samples with a ratio of B/Ti≥2.0, an apparent structural change is not observed even after annealing at 1000°C for 1 h. For samples with the ratio of B/Ti<2.0, however, there are two competitive solid phase reactions: the formation of a titanium sulicide layer at the interface and the formation of a stoichiometric TiB₂ layer at the surface, indicating the salicide (self-aligned suicide) process. The sheet resistance and the film stress in the Ti/Si and TiB_x/Si systems are explained well by the solid phase reactions.