Non-radial non-uniformity in chemo-mechanical polishing

Within-wafer non-uniformity due to chemo-mechanical polishing (CMP) is classified in this paper as belonging to two classes: radially symmetric (radial), and not radially symmetric (non-radial). While radial non-uniformity has been well-treated both theoretically and empirically in the literature, the equally important problem of non-radial non-uniformity has received little attention. We identify the significance of the latter here through a series of CMP experiments, and propose a straightforward intermediate solution.