Metal ion replenishment to plating bath.

摘要

For replenishing a metal ion to a plating bath, a soluble electrode of the same type of metal as in the bath and a counter electrode of a metal material having a nobler standard electrode potential than the soluble electrode are immersed in the bath. Electricity is conducted between the soluble electrode and the counter electrode, thereby dissolving the soluble electrode to replenish an ion of the metal of the soluble electrode to the bath. The potential of the counter electrode is measured using a reference electrode of the same metal as the soluble electrode. The quantity of electricity is controlled such that the measured potential may not be negative with respect to the reference electrode, thereby preventing deposition of the dissolving metal ion on the counter electrode while ensuring a high rate of metal ion dissolution. <IMAGE>