Development of a new generation polyurethane polishing pad used in chemical mechanical planarization of microelectronic materials

This work investigated the development of a new polyurethane polishing pad used in chemical mechanical planarization (CNT) for the manufacture of micro-electronic materials. This next generation of hard and porous pad was successfully developed at Freudenberg Nonwovens. An earlier version (FX-9) of this pad, based on licensed technology, was used as the reference for development of the Pad P.; The polymeric microspheres in the previous (FX-9) formulation were replaced with a non-woven fabric composed of three different fibers. Eliminating the microspheres enabled the forming of the new pad material at a higher temperature with shorter forming time, decreasing the forming time of the pads. Density and hardness of the new pad material was higher than the FX-9 material and the compressibility was lower. Dynamic mechanical analysis showed that the new pad was more rigid and stable at increasing temperatures compared to FX-9. The fiber network in the non-woven fabric took the role of the microspheres, to assist the wafer debris collection in CNT. Planarization rates in CMP were higher for the new pad compared to FX-9.; To correlate the polishing performance to the pad properties, a combination of pads were produced with low and high roughness, hardness and thickness. It was not possible to produce the new pad having a smooth surface finish with lower thickness. Varying the components in the formulation produced softer and flexible pads.