Abstract
The continuous miniaturization of electronic products has led to new concerns over the resistance of interconnections between transistors. As transistors become smaller and consequently faster, delays in interconnects start to account for a considerable proportion of processing time. One solution is to replace the conventional Al/SiO2 interconnects with Cu/silk interconnects. In order to curb the diffusion of Cu into silk, it has been proposed to coat the Cu with Ta. The suitability of Ta as a diffusion barrier is still not fully established. Ab initio MD simulations were carried out to characterize the diffusion of Cu and Ta atoms inside silk-like polymer structures. The results showed that Cu is much more active in the silk-like polymer than Ta. An analysis of the speed of the Cu atom in the silk polymer showed that the Cu atom experienced impulsive interatomic loads. Such impulses are postulated to cause hoppings, which were highlighted in reports of previous classical MD simulations. In contrast, the motion of Ta atom was relatively stable and can be considered as harmonic oscillations around an equilibrium position. The ‘inert’ characteristic of Ta suggests it is a good material to serve as a barrier between copper and silk layers to prevent the leakage of Cu into silk.