An empirical relation of dielectric erosion in metal chemical mechanical planarization as a function of pattern density and metal linewidth is presented in this paper. It was observed that the erosion is linearly proportional to a feature parameter defined as exp (d/d(0))\ln (w/w(0))\, where d is the metal pattern density, w is the metal linewidth, and d(0) and w(0) are constants. The slope of this formula quantifies the feature dependence of erosion performance and is affected by the slurry and the pad during metal polishing. The sign of the slope is related to the mechanism of erosion formation. (C) 2006 The Electrochemical Society.