Comparison of Interfacial Forces During Post-Chemical-Mechanical-Polishing Cleaning

This research investigates the interfacial forces involved in tribological interactions while removing nanosized particles during post-chemical-mechanical polishing cleaning. Surface and interfacial forces are discussed to understand the particle adhesion and subsequent removal through physical and chemical interactions. Approaches include theoretical analysis combined with experimental study. The theoretical analysis was focused on the forces that exist between particles and a substrate. Surface interaction consideration includes applied pressure, frictional force, and hydrodynamic drag. The polishing experiments were carried out on silicon wafers with $SiO2$ slurry. Cleaning experiments were performed in de-ionized water using a polyvinyl acetal brush to remove particles from a hydrophilic-silicon surface. The fluid-drag force was found to affect the lubricating behavior of cleaning through changing material properties. Values of interfacial forces and their effects on cleaning were discussed along with a lubricating model system.