Wafer polishing apparatus

摘要

A step part 29A is formed on a face 29 of a retainer ring 28 that contacts with a polishing pad 16 so that a wavily deformed part (16C figure 4) of the polishing pad 16 enters the step part 29A. The step part 29A is formed like a ring at the inside of the face 29 which actually contacts with the polishing pad 16. Moreover, a height (h figure 4) of the step part 29A is smaller than a thickness of a wafer 50 so that a top face of the step part 29A does not contact with the polishing pad 16 and the wafer 50 does not enter the step part 29A. Further, a width (S figure 4) of the step part 29A is set so that the wavily deformed part (16C) of the polishing pad 16 can enter the step part 29A. There may also be a sensor 70 and CPU (74 figure 4) to monitor and control the level of polishing.