Mechanic study of copper deposition onto gold surfaces by scaling and spectral analysis of in situ atomic force microscopic images

Copper electrodeposition rom three acidic solutions containing (i) no additive, (ii) 100 mu M benzotriazole, and (iii) 100 mu M thiourea was studied by in situ atomic force microscopy. The electrodeposited surfaces were analyzed on three levels: (i) qualitatively during in situ monitoring of morphology evolution, (ii) quantitatively by scaling analysis of electrodeposited surface roughness during the course of deposition, and (iii) by modeling the spectral power density of the surface shape evolution. Major differences in deposit morphology were found between the three electrolytic solutions. All three levels of analysis gave consistent interpretations of morphology evolution. Deposition from additive-free solutions leads to rough surface textures due to roughening originating from surface diffusion. Addition of benzotriazole acts to smooth the deposit by diminishing surface diffusion. Deposits grown from thiourea-containing solutions exhibit formation of three-dimensional islands atop initially flat plates, reflecting a two-stage growth mechanism.