Mechanism of surface hydrophilicity of the polishing pad during the pad break-in process

Abstract The mobility of pad molecules and water molecules during the pad break-in process was evaluated using pulsed nuclear magnetic resonance. As the removal rate increased during the pad break-in process, the crystalline and amorphous components in the pad decreased, while the gel-like component increased. The ratio of bound water to free water in the pad remained almost unchanged, but the relaxation time ( T 2 ) of free water decreased slightly. Evaluation of bound water after the break-in process using Raman scattering spectroscopy revealed that bound water was present from the pad surface to a depth of approximately 5–10 μm, but not above 20 μm. The mechanism of pad conditioning is that polar molecules such as urethane bonds and urea bonds are physically broken down by pad conditioning, and water molecules then bind to these broken-down polar molecules.