Novel slurry solution for dishing elimination in copper process beyond 0.1-μm technology

The reduction of the copper dishing was investigated by optimizing the copper CMP processes. The reduction method is a novel copper slurry with the organic passivation agent used during the copper polishing to reduce the copper dishing level. The passivation mechanism of the copper polishing was proposed. With the optimized condition of the copper ECD and CMP, the resistivity deviation of 180-μm square metal pads with 10–80% pattern densities was reduced from over 30% to less than 10%. The amount of the copper dishing was reduced from around 150 nm to less than 30 nm. Finally, 10% increase of wafer yield and better process reliability were achieved.