Modeling of chemical mechanical polishing using fixed abrasive technology

Abstract

Chemical Mechanical Polishing (CMP) is conventionally carried out using abrasive slurry and a polishing pad. An alternative process is the "fixed abrasive" polish. Existing models, which accurately predict oxide thickness variations across a chip for the conventional CMP process, have not previously been tested for the fixed abrasive process. In this study wafers were polished using the fixed abrasive pad and the data fitted against the density and step-height model. Results show that little down area polish occurs with the use of the fixed abrasive pad, except in areas of low-density. The step height model which accounts for contact height, shows improved accuracy over the density model for areas of low density. The density model however is sufficiently accurate for areas of higher density. Modeling new variants of the fixed abrasive pad may require further study and model extensions related to additional effects and pad properties.