Strong Chelating Agent Accelerated High Performance on Copper Polishing

Sustainability in Cu chemical mechanical polishing (CMP) processing for highly integrated device manufacturing demands electric energy saving and slurry consumption reduction, which can be achieved through faster CMP. A strong chelating agent, quinaldic acid (QA), was chosen to accelerate the polishing rate on Cu in an acidic H2O2-BTA system. The strong complexing capability of QA with Cu ions can facilitate the formation of a porous and loose copper oxide film on the Cu surface in acidic H2O2 solution and soften the microhardness of the Cu surface, which is beneficial for fast Cu removal in CMP process. The chemistry of QA with Cu in acidic solution was studied by electrochemical methods and physical measurements. The optimized QA containing polishing slurry produced a high Cu removal rate about 1.8 um/min with a good flatness.