Acidic chemistries for low stress planarization of Ta/Ru barrier layers

The work described herein details the development of various chemistries for low stress planarization of Ta/Ru Barrier Layers and other low-k dielectrics. We demonstrate the feasibility of a single platen, iodine-based acidic chemistry compatible CMP process that employs formation and facile removal of the soft copper iodide and ruthenium oxide layers. The use of compatible acidic chemistry (same chemicals but with different concentrations and pH) for both copper and ruthenium/tantalum polishing creates the possibility of a single platen process (instead of a three platen process) with high selectivity, at low applied down pressures (1-3 psi). Results on the CMP of Ru, Ta, and Cu are the primary focus of this report.