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Wafer edge roll-off improvement by protective agent in polishing slurry at double side polishing process

Edge flatness improvement was investigated by adding a protective agent in the polishing slurry. The protective agent was composed of water soluble polymer which had higher capability of adsorption on wafers surface as well as desorption from wafer surface by the external shear stress during polishing. The slurry including such the protective polymer could enhance the removal difference between convex and concave part more quickly than the slurry without the protective polymer. Based on this technology it was clarified that flatness creation could be effectively achieved.