Influence of Additives on Via-Filling Using Copper Electroplating

Via-filling by copper electroplating with direct current (DC) using a low copper concentration bath was studied. The effect of additives on the copper deposits was also studied by using a Vickers hardness measurement and glow discharge optical emission spectroscopy (GDOES). Via-filling was achieved with the low copper concentration bath under the selection and combination of additives. Combination of polyethylene glycol (PEG 10mg/dm3), bis (3-sulfopropyl) disulfidedisodium (SPS 10mg/dm3) and Janus Green B (JGB 10mg/dm3) as additives in the low copper concentration bath were found to be a most effective for the void-free filling. The Vickers hardness of copper deposits using various additives were measured and found out the comparatively same hardness values obtaining from additive free bath. From GDOES analysis, the component of additives in the copper films was localized at the upper part of the deposited copper films. In this report, mechanism of via-filling by copper electroplating is also discussed.