PHASE FORMATION IN CU-SI AND CU-GE

Phase formation and growth kinetics have been investigated with lateral diffusion couples in Cu-Si and Cu-Ge systems. Analytical electron microscopy was used to determine the crystal structures and chemical compositions of the growing phases. Cu3Si is found to be the dominant phase in the Cu-Si system. The growth of the silicide follows a (time)1/2 dependence with an activation energy of 0.95 eV in the temperature range of 200-260-degrees-C. Cu3Ge is the only phase observed in Cu-Ge lateral diffusion couples with its length up to 20-mu-m. The growth of Cu3Ge is a diffusion controlled process at a rate similar to that of Cu3Si. The activation energy of Cu3Ge growth is 0.94 eV at 200-420-degrees-C. In Cu-silicide or Cu-germanide formation, Cu appears to be the dominant diffusing species.