Topography study was conducted under different polishing condition, and it's impact on defectivity and in line test performance was investigated. The topography study showed that final dishing and erosion performance is mostly driven by barrier polishing condition. With existing high selectivity barrier slurry, local Cu protruded in narrow dense arrays, and slightly higher down-force can suppress the Cu protrusion. Low selectivity barrier slurry shows less topography, and affords less polishing scratch. Electrical data shows barrier polishing condition has significant impact on resistance rather than Cu clearing over-polishing step.