AFM, QCM-Dおよびエリプソメトリーを用いた銅めっき添加剤吸着状態の解析

抄録

Relationship between the adsorption state of organic additives and their suppressive effects on copper electrodeposition was studied. Adsorption on the electrode surface was characterized using atomic force microscopy（AFM）, quartz crystal microbalance with dissipation monitoring technique（QCM-D）, and ellipsometry. Suppressive effects of the additives were evaluated using polarization curves and electrochemical impedance spectroscopy（EIS）. Results demonstrated that suppressive effects did not always correlate with the QCM-D measured adsorption amount. Instead, the adsorption rates of the additives and the viscoelastic properties of the adsorbed films strongly influenced the suppressive effects. A cationic surfactant（hexadecyltrimethylammonium bromide, CTAB）can adsorb to the solid surface rapidly and can form a rigid film, giving the strongest suppressive effect among the organic additives investigated in this study. A water-soluble polymer（poly（vinyl alcohol）, PVA）forms a highly hydrated soft film on the solid surface and shows a weak suppressive effect. An anionic surfactant（sodium alkylbenzensulfonate, LAS）can adsorb to the solid surface, but because the adsorption rate is very low, the suppressive effect was very weak. In several nonionic surfactant systems, the adsorption amount and the suppressive effect were mutually correlated, qualitatively reflecting the similar structures of their adsorption films.