Copper CMP Planarity and With-in-Die Rs Improvements on 90nm Cu/Low k Interconnects

摘要

One of the benchmarks for Copper CMP performance is planarity. By optimizing copper polish down-force at different stages of the CMP process, with-in-die planarity was improved. Improvements made on planarity were shown to have corresponding gain on with-in-die Rs uniformity and Post-CMP Cu thickness uniformity across different pattern densities. With soft-landing Cu process, defectivity was also improved. For barrier polish, soft-landing had little impact on planarity or electrical properties. In this study, improvements were made over an existing 300mm Cu/low k CMP process at the 90nm node, on planarity, within-in-die Rs uniformity, and defectivity, by optimized copper process conditions.