Influence of leveler concentration on copper electrodeposition for through silicon via filling

Through silicon via technology is one of the critical and enabling technologies for 3D packaging. 300 mum deep vias with a diameter of 50 mum were filled by copper electroplating with CuSO₄ and H₂SO₄ as base electrolyte. Chloride ions, accelerator and leveler were added. The effect of leveler concentration on filling performance was studied. Electrochemical measurements were used to investigate the cathode process and the action of additives. It was found that mass transportation of copper in via became the slowest step in deep vias, small current is necessary to obtain void free deposit and only conformal growth was obtained. And with increasing of leveler concentration filling performance became better.