Improving Copper Interconnect Reliability via Ta/Ti Based Barrier

Abstract

As copper line width tightens to 100nm and below, except integration issues, reliability is another challenge. Barrier's performance is critical for the significant impact to interconnect speed and reliability. Ti based barrier is reported as an excellent barrier material from the standpoint of cost and performance, especially for the porous low-k ILD materials. While Ta based barrier is used mainly for its good adhesion, diffusion prevention. In this paper, we demonstrate a composite barrier with Ti adding to the Ta based bi-layer, which shown stable metal resistance while significantly improving reliability performance. Better interface is confirmed by TEM. Our study proved that such kind of Ti doped Ta barrier is better than the standard Ta N/Ta barrier.