摘要
In semiconductor manufacturing technologies, the Chemical Mechanical Polishing (CMP) is an important surface planarization step whose function is to render a flat surface after deposition so subsequent deposition can be carried out. The wasted CMP slurry contains valuable abrasive particles and polished wafer debris that are typically disposed without use. The abrasive particles are mechanically strong ceramic in sizes of nanometer regime, so their synthesis requires considerable energy. With rising interests in sustainable manufacturing, it becomes imperative to recycle those abrasive particles for further reuse. In this presentation, we adopt a model system consisting of alumina (Al₂O₃) serving as the abrasive, and silicon carbide (SiC) serving as the wafer debris. An electrophoretic separation scheme is explored and validated. Since particles of Al₂O₃ and SiC carry distinct surface charges, and their respective mass density is not identical, in a suspension system, they are expected to undergo different movement trajectories from the influences of vertical gravity-induced sedimentation and horizontal electrophoretic migration from an externally imposed horizontal electric field. As a result, we are able to collect powders of Al₂O₃ and SiC from different locations at the bottom of the electrophoresis cell. Detailed material characterization has been conducted to validate the effectiveness of this separation scheme. Theoretic modeling has been established to predict the movements of Al₂O₃ and SiC particles. The recycled Al₂O₃ particles have been validated as new abrasive which could provide identical polishing capability for CMP action.