Sputtered Ta-Si-N diffusion barriers in Cu metallizations for Si

Electrical measurements on shallow Si n/sup +/-p junction diodes with a 30-nm TiSi/sub 2/ contacting layer demonstrate that an 80-nm-thick amorphous Ta/sub 36/Si/sub 14/N/sub 50/ film prepared by reactive RF sputtering of a Ta/sub 5/Si/sub 3/ target in an Ar N/sub 2/ plasma very effectively prevents the interaction between the Si substrate with the TiSi/sub 2/ contacting layer and a 500-nm Cu overlayer. The Ta/sub 36/Si/sub 14/N/sub 50/ diffusion barrier maintains the integrity of the I-V characteristics up to 900 C for 30-min annealing in vacuum. It is concluded that the amorphous Ta/sub 36/Si/sub 14/N/sub 50/ alloy is not only a material with a very low reactivity for copper, titanium, and silicon, but must have a small diffusivity for copper as well.>