Smart Polishing of Hard-to-Machine Materials with an Innovative Dilatancy Pad under High-Pressure, High-Speed, Immersed Condition

An innovative dilatancy polishing pad of which characteristics are controlled with processing conditions is proposed to establish high-efficiency, high-quality polishing of hard-to-machine materials for next-generation high-power devices. To make the best use of the property of the dilatancy pad, a highly durable polishing machine which enables high-pressure, high-speed, and immersed polishing was developed. Dilatancy properties were evaluated for various viscoelastic materials to select appropriate materials for a pad. The selected viscoelastic material was mixed with a special filler and abrasive particles, and integrated into a conventional polishing pad to form a dilatancy pad. Application of the dilatancy pad to polishing of SiC realized a smart polishing which achieves both high efficiency and high quality in any processing conditions. In addition, it was demonstrated that the processing conditions could be selected for the purpose of each polishing step, i.e. mid- to high-speed conditions for high-efficiency polishing and low-speed condition for high-quality finishing. A newly developed highly durable polishing machine is capable of achieving wide range of processing conditions. To avoid overheating under high load conditions, the machine can polish a work piece in slurry fluid. The material removal rate using the dilatancy pad showed superlinear dependence on the rotation speed, which outperforms the conventional polishing following the Preston's law. This innovative process can significantly reduce the polishing time of hard-to-machine materials for next-generation semiconductor devices.