Abstract: There is disclosed a method for polishing a work wherein polishing liquid is supplied to a polishing pad, and a relative movement is carried out between the work and the polishing pad with pressing the work on the polishing pad, wherein the work of which press pressure was set to 0 to terminate polishing is released from the polishing pad within 45 seconds after the termination of polishing. When plural works are simultaneously polished, preferably only the work to which press pressure was set to 0 to terminate polishing is released from the polishing pad, and polishing of the other works is continued, which are released from the polishing pad after press pressure thereto is set 0 one by one.

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.