Electrochemical Deposition of Copper Pillar Bumps with High Uniformity

Abstract

Electrochemical deposition of copper pillar bumps (CPBs) is one of the key technologies for the advanced packaging. In this study, the effects of the additive concentration, the electrolyte convection, the current density, and the electroplating system on the uniformity of the CPBs have been systematically investigated. The results showed that the profiles of the CPBs were mainly determined by the additive concentration, the bath convection and the current density, while the heights of the CPBs were mainly affected by the electroplating system. For the CPBs profiles, it was found that the low leveler concentration and high current density would generally result in domed shape, while the uneven agitation would lead to inclined surface. For the heights of CPBs, the macroscopic uniformity could be dramatically improved by a sophisticatedly designed electroplating system. These results can provide basic guidance for the optimization of the CPBs electroplating.

Keywords

copper pillar bump / electrochemical deposition / uniformity / additive / leveler

References

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