Benzotriazole as an Additive for Copper Electrodeposition Influence of Triazole Ring Substitution

Abstract

In order to elucidate the influence of an additive on the copper electroplating process, several substituted benzotriazole compounds are used in plating 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 deposits. Using benzotriazole (BTA) or N-(1H-benzotriazol-1-ylmethyl)formamide (amide-BTA) as an additive yields the smoothest deposits. Deposition in the presence of 1-(methoxymethyl-1H-benzotriazole (MeOMe-BTA) or methyl-1H-benzotriazole (Me-BTA) results in rough deposits which resemble those obtained in the additive-free deposition. Scaling analysis was employed to analyze the AFM images. The results indicate that deposition without additives follows 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 Kardar-Parisi-Zhang model. With MeOMe-BTA or Me-BTA as additives, copper growth also follows the `Wolf-Villain+step flow' model. The images and the scaling 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 deposits were characterized by secondary ion mass spectrometry. Significant inclusion of organic matter and sulfur species was found in the deposits obtained from additive solutions.