AN INVESTIGATION OF SLURRY CHEMISTRY USED IN CHEMICAL-MECHANICAL PLANARIZATION OF ALUMINUM

Slurry chemistries for chemical mechanical planarization of aluminum w ere investigated by electrochemical measurements with a rotating disk electrode setup. The electrochemical measurements were accompanied by polishing of both blanket and patterned aluminum wafers. Results of th ese two investigations led to the development of a potassium dichromat e slurry which resulted in good surface finish and acceptable removal rates. The electrochemical measurements demonstrated the formation of a passivating layer at the surface. It was observed that in addition t o oxidizing agents in the slurry, it was essential to have etchants to obtain a smooth and clean surface. Also, the abrasives used were foun d to have a major impact on the surface finish. The slurry was success fully used in producing aluminum patterns by the Damascene process. Th e resulting polishing behavior of aluminum is explained by a balance b etween the formation of a passivating layer on the surface and dissolu tion of the abraded surface in the slurry volume near the surface.