EFFECT OF COMPOSITION ON PHASE-FORMATION AND MORPHOLOGY IN TI-SI1-XGEX SOLID-PHASE REACTIONS

The effects of Si1-xGex alloy composition on the Ti-Si1-xGex solid pha se reaction have been examined. Specifically, effects on the titanium germanosilicide phase formation sequence, C54 Ti(Si1-yGey)(2) nucleati on temperature, and C54 Ti(Si1-yGey)(2) morphology were examined. It w as determined that the Ti-Si1-xGex reaction follows a ''Ti-Si-like'' r eaction path for Si-rich Si1-xGex alloys and fellows a ''Ti-Ge-like'' reaction path for Ge-rich Si1-xGex alloys. The coexistence of multiple titanium germanosilicide phases was observed during Ti-Si1-xGex react ions for Si1-xGex alloys in an intermediate composition range, The mor phology and stability of the resulting C54 germanosilicides were direc tly correlated to the Ti-Si1-xGex reaction path. Smooth continuous C54 titanium germanosilicide was formed for samples with Si1-xGex composi tions in the ''Ti-Si-like'' regime. Discontinuous islanded C54 germano silicides were formed for samples with Si1-xGex compositions in the mi xed phase and ''Ti-Ge-like'' regimes. Using rapid thermal annealing te chniques, it was found that the C54 titanium germanosilicides were sta ble to higher temperatures, This indicated that the morphological degr adation occurs after C54 phase formation. The C54 Ti(Si1-xGex)(2) form ation temperature was examined as a function of alloy composition and was found to decrease by approximate to 70 degrees C as the compositio n approached x approximate to 0.5. An optimum Si1-xGex alloy compositi on range of 0 less than or equal to x less than or equal to 0.36 was d etermined for the formation of stable-continuous-low-resistivity-C54 t itanium germanosilicide films from the solid phase reaction of Ti and Si1-xGex alloy. The results were described in terms of the relevant nu cleation processes.