Benzotriazole as an additive for copper electrodeposition - Influence of triazole ring substitution

In order to elucidate the influence of an additive on the copper electropla ting process, several substituted benzotriazole compounds are used in plati ng solutions. Copper deposits obtained from the additive-free and additive- containing acidic solutions were examined by atomic force microscopy (AFM). Among the systems studied, additive-free deposition gives the roughest dep osits. Using benzotriazole (BTA) or N-(1H-benzotriazol-1-ylmethyl)formamide (amide-BTA) as an additive yields the smoothest deposits. Deposition in th e presence of 1-(methoxymethyl-1H-benzotriazole (MeOMe BTA) or methyl-IN-be nzotriazole (Me-BTA) results in rough deposits which resemble those obtaine d in the additive-free deposition. Scaling analysis was employed to analyze the AFM images. The results indicate that deposition without additives fol lows the "Wolf-Villain + step flow" model. Copper growth in the presence of BTA or amide-BTA is suggested to follow a different model, namely, the Kar dar-Parisi-Zhang model. With MeOMe-BTA or Me-BTA as additives, copper growt h also follows the "Wolf-Villain + step flow" model. The images and the sca ling analysis clearly show a marked effect of triazole ring substitution on the copper deposition. The different action exerted by these compounds can be explained by their ability to form oligomers with cuprous ions. The dep osits were characterized by secondary ion mass spectrometry. Significant in clusion of organic matter and sulfur species was found in the deposits obta ined from additive solutions. (C) 2000 The Electrochemical Society. S0013-4 651(00)03-037-8. All rights reserved.