Patent ID: 6508924
Filing Date: 2003-01-21
Classification: C25D,H01L

Abstract:
A method of maintaining within-wafer uniformity during the electroplating of wafers comprising controlling a level of organic additive breakdown product in an electroplating bath wherein the additive breakdown product is controlled by the method comprising the steps of: a) obtaining a plurality of plating baths where each bath has a known quantity of the additive breakdown products, but where the quantity of additive breakdown product in each bath differs from the quantity in the other baths; b) for each bath, providing a counter electrode, a cleaned working electrode and a reference electrode immersed in the bath, and equilibrating the working electrode without energy input to adsorb additive breakdown product for a period of time until the change in potential of the working electrode with time is minimal and measuring the value of the potential; c) for each bath, correlating the quantity of additive breakdown product with the value of potential obtained in step b); d) obtaining a plating bath having an unknown quantity of additive breakdown product, placing the electrodes in the bath and performing step b); e) choosing from the correlations in step c a quantity of additive breakdown product which corresponds to the equilibrated working electrode potential for the bath with the unknown quantity of additive breakdown product; and f) comparing the quantity of additive breakdown product to a preset value; provided that when the quantity of additive breakdown product exceeds the preset value, a control process is activated that reduces the quantity of additive breakdown product.