Mechanisms for the improved stability of C54-TiSi₂ on (001)Si by the addition of N₂ to Ar during Ti sputtering

Addition of N₂ to Ar during Ti sputtering has been found to improve the thermal stability of TiSi₂. For samples sputtered with a mixture of Ar and N₂, TiSi₂ was found to be stable after 1050 °C, 30 s annealing. Furthermore, the phase transformation temperature from the C49 to C54 phase was not affected with the addition of a small amount of nitrogen. The stuffing of grain boundaries of TiSi₂ and TiN/TiSi₂ interfaces by nitrogen atoms is thought to retard the transport of Si and Ti atoms. In addition, titanium nitride particles embedded in TiSi₂ near the TiN/TiSi₂ interface may also protect the TiSi₂ films from plastic deformation and retard the grain growth during high temperature annealing. Smaller average grain size of C54-TiSi₂ in samples prepared with the addition of N₂ to Ar during Ti sputtering than that in pure Ti samples is also beneficial in enhancing the thermal stability.