Copper metallization in sub-0.18mum semiconductor devices is achieved by combining the dual damascene techniques followed by chemical mechanical planarization (CMP) [1,2],Tantalum and its nitride have been identified as the diffusion barrier layer for copper metallization.However,the wide differences in properties between copper and tantalum layers result in selectivity problems during CMP process [3].Differences in chemical and physical properties between copper and tantalum lead to variations in removal rates,which may result in dishing during CMP.Therefore,it is essential to understand all the aspects of barrier metal removal for proper implementation of copper interconnect into industrial process.The aim of this work is to understand the interaction between chemical and mechanical parameters that control the polishing rates of Ta and TaN.The final goal is to obtain a better understanding on the slurry selectivity between copper and tantalum or tantalum nitride and to develop slurries with best selectivity performance.
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