Barrier CMP slurry for low topography and wide process window

Barrier CMP suffers from well-known but poorly understood EOE (fang), K value shift, dishing, erosion, and other pattern dependent problems. We developed a novel barrier slurry platform featuring minimized “fang”, and high uniformity with different pattern densities. By properly tuning the Cu/BD selectivity, the “fang” can be controlled to under 50 Angstroms. Compared to conventional barrier CMP slurries used for 55nm to 28 nm technology nodes, this novel barrier slurry contains much lower level of BD suppressor, which can effectively control Cu/BD selectivity in barrier film polishing and significantly reduce the risk of surfactant accumulation on pads and wafers, thus avoiding potential K-value shift and pad life issues. Topography evolution vs. polishing time on different pattern densities was also investigated. A wide over-polishing window is another advantage of this formulation.