| Electrodeposition technology is widely used in many applications such as electronics, copper production, and film preparation. Electrodeposit roughness is dependent on electrodeposit nucleation and growth processes, both of which are affected by mass transport and chemical additives. In this study, the effects of organic additive properties on microroughness of copper electrodeposited from chloride media are investigated.;According to the study, high molecular weight (greater than 100,000) organic additives used in this study (gelatin, PEG, PAA, PVP, and PVA) helped to reduce the surface microroughness of copper electrodeposited from chloride based media. It was found that surface microroughness on a smooth surface increased rapidly with time during the initial deposition phase. However, as the deposition time increased, the rate of increase in roughness decreased. Eventually, the steady state roughness was obtained.;From the nucleation experiments, in the presence of gelatin (high molecular weight organic additive) in the chloride based solution, the baseline nucleation rate (Ninfinity) was about 60% higher than without organic additives, which play an important role in obtaining smooth electrodeposits. Also, the initial growth experiments (the initial growth of copper electrodeposits on the surface with columns and holes) demonstrated that the mobility of additive molecules relative to depositing ions initially influenced the copper electrodeposition in the chloride based media. The presence of the adsorbed high molecular weight additives served to level or smooth the surface. The presence of the adsorbed high molecular weight additives helped to prevent anomalous growth. Hence, high molecular weight organic additives even encouraged growth on the normal surfaces, which served to level or smooth the surface. Thus, in the presence of gelatin, the nucleation process became more dominant than the growth process. In other words, the presence of gelatin implemented the nucleation process to control the quality of the copper electrodeposits. This resulted in a smooth and dense copper electrodeposit from the chloride based media.;The effect of organic additive size on nucleation was studied to understand why the high molecular weight additives increased the nucleation rate density. Based on the experimental (SiO2 system and PEG and PEO system) and theoretical results, a method of evaluating the effect of size on nucleation rate was evaluated and found to be useful. |
