A new Paradigm for Polyurethane CMP Pads: Tailoring Phase Mixing and Surface Polarity via CO2-based Polyols for Advanced CMP Performance

Recent semiconductor manufacturing trends demand not only high polishing performance and defect control, but also sustainable materials throughout the CMP process. Conventional polyurethane (PU) CMP pads have primarily relied on petrochemical raw materials, raising concerns regarding carbon emissions and sustainability. To overcome these limits, this study proposes a new paradigm by introducing CO2-based polyols into the PU pad matrix, marking one of the pioneering attempts to apply carbon-captured polymers to CMP pads.

In this study, the CO2-based CMP pads were fabricated via hybrid foaming casting. To elucidate the underlying macromolecular mechanisms, structural and viscoelastic behaviors were investigated using WAXS/SAXS and dynamic mechanical analysis (DMA). Interestingly, WAXS/SAXS profiles and DMA results revealed that the high polarity of CO2-based polyol induced phase mixing between the hard and soft segments, fundamentally altering the storage modulus (E') and tan δ behavior. Furthermore, nanoindentation confirmed an increased surface hardness, while surface zeta potential measurements showed enhanced negative charge under alkaline conditions.

Particular attention was given to the interactions between pad surface behavior and polishing performance during oxide/nitride CMP processes using ceria/silica slurries. The CO2-based pad maintained a removal rate comparable to conventional pads while achieving a dramatic reduction in polishing defects. This defect mitigation is directly attributed to the optimized surface polarity and enhanced electrostatic repulsion at the pad-wafer-slurry interface, driven by the highly negative pad surface.

Overall, this work demonstrates that transitioning to sustainable polymer platforms not only addresses ecological concerns but also offers unexpected breakthroughs in tuning microphase morphology and interfacial thermodynamics, paving the way for next-generation, eco-performance semiconductor manufacturing.