Effect of Slurry Selectivity on Dielectric Erosion and Copper Dishing in Copper Chemical-Mechanical Polishing

A formidable challenge in the present multi-step Cu CMP process, employed in the ultra-large-scale integration (ULSI) technology, is the control of wafer surface non-uniformity caused by dielectric erosion and Cu dishing. A definitive understanding of the causes of material loss and a physical model for non-uniformity in Cu CMP are thus required. This paper examines the effects of slurry selectivity on dielectric erosion and Cu dishing, in both single- and multi-step Cu CMP processes, in terms of several geometrical and physical parameters. Furthermore, optimal slurry selectivities to mitigate dielectric erosion and Cu dishing in both single- and multi-step polishing are suggested.