Abstract: At the conclusion of chemical mechanical polishing (CMP) there is found to be a topography difference at the periphery of the wafer. For example, for a 200 mm wafer, the oxide surface in a peripheral region up to 20 mm wide, may end up about 1,000 Å above or below the central portion of the surface. This problem has been overcome by varying the type of polishing pad and retainer ring from one CMP operation to the next. Thus, if the equipment that is used to effect a given CMP step results in a post CMP surface in which the periphery of the wafer is higher than the center, CMP equipment for the next layer is selected that, operating alone, would result in a surface in which the periphery of the wafer is lower than the center. The two CMP operations thus cancel each other and a uniformly flat final surface results. The conditions required to produce either surface topography are described and discussed.