Reduction of CMP μ-scratch induced metal shorts by introduction of a post CMP tungsten plasma clean process in a high volume DRAM manufacturing environment

A common problem of tungsten CMP processes used in damascene sequences is the generation of μ-scratches. These scratches form small trenches in the oxide, which are filled with tungsten during the CMP process. These metal filled trenches can short the intended patterned circuitry. By introduction of a dry plasma clean after the tungsten CMP process, the yield impact of these scratches can be reduced or eliminated: The plasma etch process removes tungsten uniformly both from the intended metal pattern and the unintended metal residue in the scratch trench. The metal short can be eliminated by adjusting the etch depth to the actual scratch depth.