We describe an investigation into the pattern dependence of dishing and erosion during the chemical-mechanical polishing of copper used for delineating inlaid metal patterns. Copper dishing is determined to be highly dependent on the width of the copper structure, but only minimally dependent on the density of copper structures. Erosion of the SiO2 dielectric layer is strongly affected by the pattern density, but not affected by changes in the width of the copper lines. As a result, both line width and pattern density are important considerations in predicting the final thickness of the copper lines.