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Abstract

An improvement is proposed in the cleaning treatment of semiconductor silicon wafers in which the conventional step of cleaning with an aqueous solution of an alkali is replaced with a cleaning treatment with a temporarily alkaline pure water which is produced electrolytically by the application of a DC voltage between a cathode and an anode bonded to the surfaces of a hydrogen-ion exchange membrane so that the alkaline cleaning treatment can be performed under mild conditions so as to eliminate the troubles due to formation of COPs unavoidable in the conventional process. In addition, the pure water rinse following the alkali cleaning of the wafers before transfer to the succeeding acidic cleaning step can be omitted to greatly contribute to the improvement of productivity. The apparatus used therefor comprises a rectangular vessel divided into a central cathode compartment, in which the wafers are held in a vertical disposition within an up-flow of pure water, and a pair of anode compartments by partitioning with a pair of hydrogen-ion exchange membranes, on both sides of which a cathode plate and anode plate are bonded.

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