Nucleation and Growth of Electrodeposited Cobalt onto Si/Cu(111) substrate

The electrochemical nucleation and growth of Co onto (111) textured Cu film on monocrystalline Si was studied. Nucleation experiments were carried out depositing Co from pH 6 sulfamate solutions by standard electrochemical methods. AFM and SEM were used to characterize nuclei distribution and morphology. The nucleation mechanism was qualitatively probed by comparing experimental current transients to theoretical transients according to the Sharifker et Hills model. The type of nucleation mechanism is apparently related to the Co concentration and the overpotential. Increase of either cathodic potential or Co concentration causes a shift from instantaneous to progressive nucleation. The results of the amperometric analysis were not confirmed unequivocally by morphological examination of Co deposits. The mechanism of Co nucleation from simple sulfamate solution on Si/Cu(111) substrate is instantaneous in nature. Highly (00.1) textured Co deposits can be obtained in these conditions, though not necessarily with preservation of the fine columnar microstructure.