Titanium germanosilicide phase formation during the Ti-Si _1-xGe _x solid phase reactions

The effect of Si _1-xGe _x alloy composition on the titanium germanosilicide phase formation sequence during the Ti-Si _1-xGe _x solid phase reaction was examined. For the Ti-Si reaction the initial formation of C49 TiSi ₂ is followed, at higher temperatures, by the formation of C54 TiSi ₂. For the Ti-Ge reaction the initial formation of Ti ₆Ge ₅ is followed, at higher temperatures, by the formation of C54 TiGe ₂. It was determined that the Ti-Si _1-xGe _x reaction follows three different reaction paths depending on the composition of the initial Si _1-xGe _x alloy. For Si rich Si _1-xGe _x alloys the Ti-Si _1-xGe _x reaction follows a 'Ti-Si like' reaction path (Ti+M → C49 TiM ₂ → C54 TiM ₂, where M = Si _1-xGe _x). For Ge rich Si _1-xGe _x alloys the reaction follows a 'Ti-Ge like' reaction path (Ti+M → Ti ₆M ₅ → C54 TiM ₂). Both Ti ₆M ₅ and C49 TiM ₂ form during the reaction of titanium with Si _1-xGe _x alloys in an intermediate composition range. Properties of the final C54 phase were observed to be strongly dependent on the phase formation sequence. Smooth continuous C54 titanium germanosilicide forms during the 'Ti-Si like' reaction and discontinuous islanded C54 titanium germanosilicide forms during the 'Ti-Ge like' reaction. An optimum Si _1-xGe _x alloy composition range of 0.00 ≤ x ≤ 0.36 was determined for the formation of continuous-low-resistivity- C54 titanium germanosilicide films from the solid phase reaction of Ti and Si _1-xGe _x alloy.