Patent ID: 6402589
Filing Date: 2002-06-11
Classification: B24B

Abstract:
A wafer polishing apparatus comprising:a rotatable polishing stool having a polishing cloth on a surface thereof and having a polishing tool rotational shaft; a carrier rotated about a rotational shaft parallel to but different from the polishing tool rotational shaft for bringing a wafer into contact with said polishing cloth under a predetermined pressure; a pad arranged around said wafer in such a manner as to contact said polishing cloth under a predetermined pressure; a detector for detecting change in relative positions of the back of said wafer or said carrier and said pad, the detector providing a detection signal; an operating unit for computing a computed polishing quantity by processing the detection signal of said detector; and a control unit for controlling polishing operation in accordance with the computed polishing quantity; said operating unit including: a sampling unit for sampling the detection signal of said detector with such a sampling period that the number of times sampled per rotation of said polishing stool is plural, the sampling unit providing sampling data; a moving average calculating unit for calculating moving average data by averaging the sampling data in the number equal to an integer multiple of the number of times sampled per rotation; and a polishing quantity computing unit for computing the polishing quantity from said moving average data.