Effect of the inhibiting action of additives on the macro- and microdistribution of copper during electrodeposition from sulfuric acid electrolytes

• A.A. Kosarev, A.A. Kalinkina and T.A. Vagramyan

Russian University of Chemical Technology named after D.I. Mendeleev, Miusskaya sq., 9, 125047 Moscow, Russian Federation

Abstract: The paper studies the effect of electrodeposition conditions on the uniformity of copper distribution and the morphology of copper coatings both on the surface and in small-diameter through holes. In order to improve the coating uniformity, a complex additive based on polyalkylene glycols, nitrogen-containing heterocyclic compounds and organic sulfur-containing compounds was used. The results were compared with those obtained for coatings deposited from an electrolyte containing only copper sulfate and sulfuric acid but no additives. Based on a significant increase in cathodic polarization in the presence of the complex additive, an inhibitory effect on the copper electrodeposition was assumed. The electrodeposition of copper onto samples with through holes was carried out under direct current and in reverse mode. The introduction of the complex additive into the electrolyte nearly does not change the roughness parameters Ra and Rz , however, it significantly affects the morphology of copper coatings obtained under direct current. It was found from the micrographs of cross-sections that the presence of the complex additive in the electrolyte without current reversal results in the formation of a flat wavy microrelief of the copper coating surface. The micrographs of the outer surface of the samples confirmed the three-dimensional shape of the microwaves whose height reaches ~30–40% of the average thickness of the copper deposit. Under current reversal conditions without the complex additive, the microrelief has nearly no waviness, however, a dendritic surface with significant crystal roughness is formed. Coatings that are uniform in thickness and structure are formed on the surface of the samples and in the holes only provided that current reversal, the complex additive, and stirring of the electrolyte are used simultaneously.

Keywords: inhibiting additives, roughness, metallization of through holes, leveling, copper microdistribution

Int. J. Corros. Scale Inhib., 2020, 9, no. 3, 967-978 PDF (513 K)
doi: 10.17675/2305-6894-2020-9-3-11

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