PURPOSE: To facilitate mirror surface polishing of the upper surface only of a semiconductor wafer by a method wherein an upper surface plate is turned to the same direction as the direction of revolution of a carrier and a lower surface plate is turned to the opposite direction to make the difference between respective relative speeds large.
CONSTITUTION: Both a sun gear 22 and an internal gear 23 turn clockwise. If the rotation speed Ns of the gear 22 the rotation speed Ni of the gear 23, a carrier 21 makes rotation clockwise and makes revolution clockwise with the speed corresponding to the difference between Ns and Ni. Under this condition, an upper surface plate 24 is turned coutner-clockwise with the rotation speed NA and lower surface plate 25 is turned clockwise with the rotation speed NB. If the revolution speed of the carrier 21 is NC, the polishing speed is approximately proportional to (NA+NC) on the upper surface of a semiconductor wafer 11 and approximately proportional to (NBC-NC) on the lower surface of the semiconductor wafer 11. Therefore, by selecting NA, NB and NC properly, the upper surface of the wafer 11 can be finished into a mirror surface where no deteriorated layer produced by processing remains.
ITOU YOSHITERU
SHIROKAWA JUNJIRO
KASHIYANAGI YUZO
