The stability and composition of the Ni-germanosilicided films formed on relaxed Si1-xGex alloy has been studied in the temperature range of 400-900 degreesC. During the solid phase thermal reaction between Ni and Sil(1-x)Ge(x), a nickel-germanosilicide Ni-y(Si1-wGew)(1-y) ternary phase (wless than or equal tox and yapproximate to0.5) and a Ge-rich Si1-zGez phase (z>x) have been found. In the lower annealing temperature range of 500degreesC, the Ge composition in the nickel-germanosilicide phase is similar to that of the Si0.75Ge0.25 substrate. At the same time, germination of Si1-zGez (z>x) takes place within the germanosilicide film. At higher annealing temperatures, Ni thermodynamically prefers to react with Si compared to Ge, and as a result, Ge segregates out from the germanosilicide grains to enrich Ge in the formed Si1-zGez (z>x) grains in between the germanosilicide grains. On the other hand, the size of the germanosilicide grains increases almost linearly with annealing temperature while that for the Si1-zGez grains remains almost constant up to an annealing temperature of 700 degreesC, and above which it increases sharply. As a result, the Ge-rich Si1-zGez grains make the germanosilicide film discontinuous, leading to an increase in the sheet resistance of the germanosilicide film. (C) 2004 American Vacuum Society.