Metal-induced line width variability challenge and mitigation strategy in advanced post-Cu interconnects

This study illustrates that the mechanism of line wiggling (repetitive line CD variability) caused by post-Cu alternative metals deposition can be characterized by a “zipping up” behavior of alternative metals, which is related to their surface energy. The repetitive line CD variability caused a line resistance increase, which resulted in overall circuit performance degradation. It has been observed that the extent of line wiggling has strong dependencies on several parameters such as A/R (Aspect Ratio) of trenches and the modulus of IMD (Inter Metal Dielectric). We have demonstrated Ru interconnects without line wiggling by using a sacrificial TiN template which is replaced with low-k material after line fabrication.