Surface roughness evolution for Cu electrodeposition on microelectrodes

We have used atomic force microscopy (AFM) to measure the surface roughness of Cu films electrodeposited on photolithographically patterned microelectrodes. The data is consistent with anomalous scaling, where both the local and large-scale roughness show a power law dependence on the film thickness. Our results point to the role of diffusion control in determining the scaling behavior. Although the current distribution was nonuniform, and both the film thickness and roughness were greater near the edge than at the center, the scaling exponents were the same wherever measured. Data from both the center and near the edge lie on a single line when saturation roughness w(sat) is plotted against correlation length l(c).