Characterization of Sputtered Titanium Carbide Film as Diffusion Barrier for Copper Metallization

In this study, the physical and electrical properties as well as thermal stability of sputter-deposited titanium carbide films as diffusion barriers for Cu metallization were investigated for the first time. With thermal annealing in ambient for 30 min, the unpatterned Cu (2000 Å)/ (500 Å)/n-Si structure was found to be metallurgically stable up to a temperature between 600 and 650°C without formation of a phase, while the reverse leakage current of the patterned Cu (2000 Å)/ (500 Å)/ diode structures showed that the barrier layer was capable of withstanding annealing temperatures up to 500°C. The failure of the layer after high temperature annealing is attributed to the diffusion of Cu along localized defects or grain boundaries of the barrier layer into Si substrate, which caused the high junction leakage currents for the patterned structure and formation of for the unpatterned structure.