Electrical and structural properties of zirconium germanosilicide formed by a bilayer solid state reaction of Zr with strained Si1-xGex alloys

Contributors:   Z. Wang, D.B. Aldrich, Robert J. Nemanich, and D.E. Sayers

ABSTRACT

The effects of alloy composition on the electrical and structural properties of zirconium germanosilicide (Zr-Si-Ge) films formed during the Zr/Si1-xGex solid state reaction were investigated. Thin films of Zr(Si1-yGey) and C49 Zr(Si1-yGey)2 were formed from the solid phase reaction of Zr and Si1-xGex bilayer structures. The thicknesses of the Zr and Si1-xGex layers were 100 and 500 Å, respectively. It was observed that Zr reacts uniformly with the Si1-xGex alloy and that C49 Zr(Si1-yGey)2 with y = x is the final phase of the Zr/Si1-xGex solid phase reaction for all compositions examined. The sheet resistance of the Zr(Si1-yGey)2 thin films was higher than the sheet resistance of similarly prepared ZrSi2 films. The stability of Zr(Si1-yGey)2 in contact with Si1-xGex was investigated and compared to the stability of Ti(Si1-yGey)2 in contact with Si1-xGex. The Ti(Si1-yGey)2/Si1-xGex structure is unstable when annealed for 10 min at 700°C, with Ge segregating from Ti(Si1-yGey)2 and forming Ge-rich Si1-zGez precipitates at grain boundaries. In contrast, no Ge segregation was detected in the Zr(Si1-yGey)2/Si1-xGex structures. We attribute the stability of the Zr-based structure to a smaller thermodynamic driving force for germanium segregation and stronger atomic bonding in C49 Zr(Si1-yGey)2. Classical thermodynamics were used to calculate Zr(Si1-yGy)2-Si1-xGex tie lines in the Zr-Si-Ge ternary phase diagram. The calculations were compared with previously calculated Ti(Si1-yGey)2-Si1-xGex tie lines.

Publisher: Journal of Applied Physics,   Volume: 82,   2342-2348 ||  Published: 1997-09 ||   PDF (922.34 KB) ||   Read more...