Frictional Behavior and Topography of Porous Polyurethane on Copper and Silicon Dioxide Articulating Contacts

Frictional behavior and topographical changes of material surfaces with applications in the microelectronics industry were experimentally observed. This work was performed to unveil trends in tribological characteristics of porous polyurethane material separately against copper and silicon dioxide materials typically found in integrated circuit (IC) polishing manufacturing processes. A linear reciprocating tribometer was utilized to translate the loaded contact of the polymer and contacting materials in the presence of a colloidal silica slurry. Contact forces were monitored throughout the experiments while surface topography of contacting surfaces was quantified using profilometry. Trials of polishing experiments were performed through a range of normal pressures and velocities to identify trends of interest, which are important in polishing. Coefficients of friction (COFs) between the polymer and contacting materials showed a decreasing trend with increasing polishing time and distance traveled. The copper and polymer material contacts were found to have a lower COF than that for the silicon dioxide and polymer contacts. Surface roughness of the polymer showed a general decreasing trend with increasing polishing time. This trend indicates a potential correlation between polymer surface roughness and the COF between the polymer and contacting materials. Evolution of the surface roughness of the materials differed depending on the direction along which topography was measured. An uncertainty analysis of the quantified parameters was conducted to provide knowledge in the confidence of the experimental results. Tribological behavior of the porous polyurethane and copper and silicon dioxide contacts is gathered from this experimental work for more complete characterization of the material.