Effects of pressure on electroplating of copper using supercritical carbon dioxide emulsified electrolyte

Electroplating of Cu with supercritical CO2 emulsion (SCE) is studied to clarify the effects of SCE in the electroplating reaction. Properties of the SCE can be adjusted by pressure. Size and size distribution of the dispersed phase are reduced by increasing pressure, which is expected to promote the transfer efficiency of Cu2+ into the diffusion layer and causes a decrease in on-time of the periodic-plating-characteristic in the electroplating with SCE (ESCE). A minimum value for both surface roughness and grain size was observed for the Cu films electroplated at 15 MPa when pressure was increased from 9 to 21 MPa. The most positive potential response was observed for ESCE also at 15 MPa in chronopotentiometry. Therefore, we believed a critical size for the dispersed phase was reached at roughly 15 MPa to cause the phenomena observed.

► Study application of supercritical CO2 emulsion (SCE) in Cu electroplating.
► Study effects of pressure on properties of Cu films electroplated with SCE.
► A minimum value of both surface roughness and grain size is observed at 15 MPa.
► The properties are believed to be mostly affected by the size of the dispersed phase.