Anomalous Scaling for Thick Electrodeposited Films

Abstract

Anomalous surface roughness scaling, where both the local and the large-scale roughness show a power-law dependence on the film thickness, has been widely observed. Here we show that the value of the local roughness exponent in the early stages of Cu electrodeposition depends on the deposition potential. However, initial anomalous scaling can lead to two qualitatively different types of behavior for large film thickness (t>/ or =4 microm). For Cu films electrodeposited with forced convection at high potential and current density, the anomalous scaling is transient: the local roughness saturates for the thickest films studied. When Cu films are electrodeposited at similar potential and current density but with reduced convection, no saturation of the local roughness is observed. Instead the film forms overhangs such that the surface height becomes a multivalued function of the lateral position.