Effect of Oxygen on Working Life of Additives and Improved Design of Anode Bag in Copper Electroplating

The research studied the degrading and consuming phenomena of organic additives caused by oxygen generated by the insoluble anode in the process of copper electroplating. A double-layer anode bag was designed to prevent the additive ions from approaching the anode and getting degraded. Nitrogen bubbles of a particular size were injected into the anode bag gap to help capture dissolved oxygen molecules and merge with tiny oxygen bubbles coming from the anode. Therefore, the total surface area and number of oxygen bubbles were reduced, the oxygen concentration in the merged bubbles was diluted, and the amount of dissolved oxygen in the electrolyte was lowered. The improved design of anode bag with nitrogen purging slowed down the degrading rate and elongated the working life of the additives, and thereby cut down the production cost. In addition, a recycle system was designed to remove oxygen from nitrogen for reuse of nitrogen.