ANURAG JINDAL, SHARATH HEGDE & S.V. BABU, Clarkson University, Potsdam, NY, USA
Chemical Mechanical Polishing (CMP) has been widely recognised as the only viable technique to eliminate topographic variations and accomplish global planarisation for Ultra Large Scale integrated (ULSI) circuits. Slurry forms an integral part of a typical CMP process. Conventional slurries contain single type of abrasives and suffer from issues such as polish rate selectivity, surface quality and slurry stability. Recently, we have proposed formulation of Mixed Abrasive Slurries (MAS) to overcome some of these issues [1, 2]. MAS is a suspension of two or more types of abrasive particles in a chemical solution. This paper discusses the results on metal polishing using MAS containing a mixture of alumina and silica particles. These slurries demonstrate high selectivity to tantalum with an improved surface quality during copper damascene CMP process. This improved CMP performance is explained based on the particle-particle and particlesurface interactions.