The Influence of Inorganic Fillers in TDI-based Polyurethane Pad for Sapphire Substrate Chemical Mechanical Polishing

A polishing pad plays a crucial role in chemical mechanical polishing (CMP) of semiconductor fabrication. Among the CMP pads, polyurethane (PU) pads have been widely applied in global planarization of sapphire substrate surface due to their unique surface morphology, excellent durability, and long lifetime. Nevertheless, the effect of various fillers in the pores of pads and their variation in the pad performance during CMP have been rarely reported. In this study, TDI-based polyurethane (PU) composites incorporating various inorganic fillers, including barium sulfate (BaSO 4 ), cerium oxide (CeO 2 ), α -alumina ( α -Al 2 O 3 ), and calcium carbonate (CaCO 3 ), were prepared for polishing sapphire substrates. The size and morphology of the inorganic fillers used for CMP pads have been systematically characterized because of their impact on resultant polished surface. After processing, the surface roughness (Ra) of the sapphire substrate decreased to 0.346 nm using PU/BaSO 4 , representing a 37% improvement compared to the substrate without filler due to BaSO 4 having better wear resistance and excellent compatibility in the PU matrix. Additionally, there was a 15% increase in the material removal rate. This study introduces an innovative, cost-effective, and scalable production technique for PU-based CMP pads, achieving ultrasmooth and efficient sapphire planarization.