Novel Pure Organic Particles for Copper CMP at Low Down Force

It is generally accepted that there is a minimum hardness requirement for abrasive particles to be used in CMP (Chemical Mechanical Polishing) slurries. For copper CMP, the common abrasives are various types of alumina and silica. It has also long been suspected that a softer organic based abrasive could significant reduce the defects during polishing. In this study, for the first time, we demonstrated the usefulness of an organic particle as abrasive in formulating copper CMP slurry. The unexpected consequence of using such soft hydrophilic particles is its low sensitivity of material removal rate for copper towards polishing down force and platen speed. In addition, due to its unique particle surface properties, the slurry gives high selectivity in removal rate for copper over barrier, cap, and dielectric materials. In this paper, some basic physical and chemical characteristics of the particles and slurry will be first presented. The performance of this new slurry in relation to conventional slurries on blanket and patterned wafers will be discussed