The effects of alloy composition on the electrical and structural properties of zirconium germanosilicide (Zr–Si–Ge) films formed during theZr/Si1−xGexsolid state reaction were investigated. Thin films ofZr(Si1−yGey)and C49Zr(Si1−yGey)2were formed from the solid phase reaction of Zr andSi1−xGexbilayer structures. The thicknesses of the Zr andSi1−xGexlayers were 100 and 500 Å, respectively. It was observed that Zr reacts uniformly with theSi1−xGexalloy and that C49Zr(Si1−yGey)2withy=xis the final phase of theZr/Si1−xGexsolid phase reaction for all compositions examined. The sheet resistance of theZr(Si1−yGey)2thin films was higher than the sheet resistance of similarly preparedZrSi2films. The stability ofZr(Si1−yGey)2in contact withSi1−xGexwas investigated and compared to the stability ofTi(Si1−yGey)2in contact withSi1−xGex.TheTi(Si1−yGey)2/Si1−xGexstructure is unstable when annealed for 10 min at 700 °C, with Ge segregating fromTi(Si1−yGey)2and forming Ge-richSi1−zGezprecipitates at grain boundaries. In contrast, no Ge segregation was detected in theZr(Si1−yGey)2/Si1−xGexstructures. We attribute the stability of the Zr-based structure to a smaller thermodynamic driving force for germanium segregation and stronger atomic bonding in C49Zr(Si1−yGey)2.Classical thermodynamics were used to calculateZr(Si1−yGey)2–Si1−xGextie lines in the Zr–Si–Ge ternary phase diagram. The calculations were compared with previously calculatedTi(Si1−yGey)2–Si1−xGextie lines. ©1997 American Institute of Physics.