Characterization of cobalt thin films electrodeposited onto silicon with two different resistivities

Electrodeposition appears as an option to obtain thin films of technological interest. In the present study, galvanostatic and potentiostatic deposition of cobalt films onto n-type Si(100) with two different resistivities, < 0.005 Ω cm and 50–100 Ω cm, was performed. The influence of silicon resistivity on electrochemical parameters and on nucleation features was investigated by chronogalvanometric and chronopotentiometric curves. Atomic force microscopy characterization of the deposits indicated that electrochemical parameters and the deposition method (galvanostatic or potentiostatic) influence the morphology of the deposits. For potentiostatic deposition an instantaneous nucleation was found and the cobalt nuclei deposited onto low silicon resistivity were smaller in size and greater in quantity than those onto high silicon resistivity. For galvanostatic deposition a progressive or two-step nucleation was observed without significant influence of the substrate resistivity on deposit morphology.