Abrasive‐Free Polishing for Copper Damascene Interconnection

A complete abrasive-free process for fabricating copper damascene interconnection has been developed. The process is a combination of newly developed abrasive-free polishing (AFP) of Cu and dry etching of a barrier metal layer. A new aqueous chemical polishing solution and a polyurethane polishing pad produce complete stop-on-barrier characteristics of Cu polishing. The AFP provides a very clean, scratch-free, anticorrosive polished surface, and the total depth of erosion and dishing is reduced to less than one fifth of that produced by conventional slurries, even after 100% overpolishing. The barrier metal is successfully dry etched by using SF 6 gas at a high selectivity ratio (more than 10) of barrier metal to SiO 2 . It was found that the developed AFP significantly reduces both Cu line resistance and its deviation. Moreover. AFP can also contribute to cost reduction of chemical mechanical polishing and help solve environmental problems related to waste slurries.