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

Abstract

In order to investigate the effects of vacuum annealing on the properties of titanium boride films (TiBx) on a (100)Si substrate, TiBx/Si samples were prepared by the co-evaporation process and then annealed in the temperature range of 300≈1000°C. The interfacial reaction of TiBx/Si systems and the thermal stability of non-stoichiometric TiBx 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 TiBx 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 silicide layer at the interface and the formation of a stoichiometric TiB2 layer at the surface, indicating the salicide (self-aligned silicide) process. The sheet resistance and the film stress in the Ti/Si and TiBx/Si systems are explained well by the solid phase reactions.