Abstract: There is disclosed a method of manufacturing semiconductor wafers, in which a lapping process is performed prior to a chamfering process. This makes it possible to manufacture semiconductor wafers while maintaining the smoothness and dimensional accuracy of a chamfered surface of each wafer obtained by the chamfering process.

Abstract: The invention provides a novel apparatus for the wet treatment, e.g. chemical etching treatment, of a plural number of wafer materials such as wafers of high purity silicon semiconductors. The apparatus comprises a liquid tub for containing the treatment liquid, e.g. etching solution, a pair of screw shafts horizontally held in the liquid tub in parallel with each other to be rotatable in the same direction at the same velocity to serve as a kind of screw conveyor and a traveling drum carriage mounted on the screw shafts as engaged with the threads of the shafts at the circular end plates so as to be rotated and transferred in the treatment liquid simultaneously as the screw shafts rotate.