Investigations of solution variables in a contactless copper electrodeposition process for 3D packaging applications

A novel electrochemical method for contactless electrodeposition of copper onto silicon wafers has been investigated. Deposition parameters such as applied current, concentrations of deposition solution and supporting electrolyte were optimized to achieve high deposition rates as well as homogenous deposition of copper. Copper sulfate solution temperature of about 65 °C was shown to be suitable for achieving stable and high values of current density that translated to copper deposition rates of~2.4 µm/min with good deposition uniformity.