Grain boundary diffusion, electromigration and segregation in Cu and Cu-2wt%Sn alloy

We have studied grain boundary diffusion of Cu-67, and Sn-113 radioactive tracers in pure Cu and the Cu-2wt.%Sn alloy over 250 - 600 degrees C. The grain boundary self diffusion coefficients in Cu are described by an activation energy of 0.92eV and the pre-exponential factor delta D-o(0)=1,56x10(9) cm(3)/sec which are in close agreement with those reported by Surholt et al, [1] recently, In the Cu-2wt%Sn alloy, however, the activation energy for the host atom grain boundary diffusion gets enhanced significantly by about 0.4eV, It has also resulted in concurrent enhancement of electromigration life times by several orders of magnitudes and increased activation energy by about the amount [2] in the thin film conductors, These findings are of vital importance to the semiconducting industry which has set a goal of Cu substitution, because of its higher conductivity, for Al in the computer interconnections in the next decade [3], It has also been possible to obtain parameters for grain boundary segregation in the Sn/Cu system from the diffusion data themselves which will be discussed.