Development of High-Speed Rotation Polishing System with Slurry Confinement and Friction-State Control

An increased removal rate is required to improve the production efficiency during the polishing of ultrahard-to-process materials. The rotational speed of the polishing pad is increased to increase the removal rate. However, research has not been extensively conducted on polishing with a high-speed rotation because slurry is rarely supplied to a polishing area by the centrifugal force generated through polishing pad rotation. In this study, we developed a high-speed rotational polishing system with slurry confinement and friction-state control. The casing and spiral groove of the polishing pad were designed to confine the slurry in a polishing area, and friction-state control was adopted to maintain the spindle torque generated by friction between the pad and wafer at the target spindle torque. Based on the experiments investigating the supply efficiency, the developed polishing method can supply sufficient slurry to the polishing area by the optimized spiral groove pattern and perform polishing without slurry shortage at a high-speed pad rotation of 10000 min-1. In addition, the results of polishing experiments for a sapphire wafer revealed that friction-state control and wafer rotation could stabilize the polishing state effectively. The proposed polishing system can achieve a higher removal rate than the conventional polishing system.