A comparison of typical additives for copper electroplating based on theoretical computation

Abstract Electronic parameters of four additives for copper electroplating including accelerators, mercaptopropane sulfonic acid (MPS) and bis-(acid-sulfopropyl)-disulfide (SPS), inhibitor polyethylene glycol (PEG)and leveler Janus Green B (JGB). They were computed by using DFT/B3LYP method based on the 6-311G + (d, p) basis set. The quantum chemical parameters, which were most relevant to the interaction between the additives and copper surface, were calculated in the gas and aqueous phases for comparison. The condensed Fukui function analysis, molecular electrostatic potential plots and the average local ionization energy plots were applied to predict the most active site(s) of those molecules. Molecular dynamic simulations were also employed to examine the adsorption energies and the adsorption configurations of these additives on Cu (1 1 1) surface under the water environment at 298 K and 323 K conditions. As a result, compared with the other additives in copper electroplating, the unsaturated functional group is an essential factor to levelers. Hence, we predict a novel additive structure according to our calculation results.