Effects of current density and deposition time on electrical resistivity of electroplated Cu layers

Abstract

This study was performed to investigate the effects of current density and deposition time on sheet resistance and resistivity of electroplated Cu layer. Cu layer covered on sputtered Si/Ta/22Cu-78Ta/Cu films was electroplated with current densities of 1, 1.5 and 2 A/dm2, and the deposition times varied from 20 to 100 min. The effects of current density and deposition time on the thickness of Cu layers and the current efficiency were investigated. The variation in sheet resistance and resistivity were discussed with respect to thickness, surface roughness, microstructure, grain size, and texture. In general, it was found that surface roughness might not be the dominate parameter, but the density of nodule boundary in the porous films would affect the electrical property of the electroplating Cu. An increasing extent of the (1 1 1) preferred orientation tends to loosen the nodules and lower the sheet resistance and resistivity of Cu layers. A decrease in the current density and an increase in deposition time tend to produce a Cu layer with (1 1 1) preferred orientation and results in relatively low sheet resistance and resistivity.