The inhibitive effect of benzotriazole on a commercial copper surface ͑phosphorus-deoxidized copper͒ was studied by a scanning electrochemical microscope ͑SECM͒ in an aqueous sodium sulfate solution using ferrocenemethanol ͑FcMeOH͒ as the redox mediator. The formation of the inhibitive film was followed as a function of time and as a function of the potential of the copper substrate. The results were analyzed using the existing models in the literature. The results show that the potential has a crucial effect on the growth of the ͓Cu͑I͒-BTA͔ film. At a potential close to the dissolution range of copper, the surface changes gradually from almost ideally conductive to almost ideally insulating surface in the presence of benzotriazole, but at more negative potentials the effect is diminished and finally deceased. Quartz crystal microbalance experiments showed that the mass of an adsorbed layer must correspond to a multilayer.

The inhibition of copper corrosion by benzotriazole ͑BTAH͒ has been studied by scanning electrochemical microscopy as a function of time and oxygen content. Under normal atmospheric conditions the inhibiting ͓Cu͑I͒-BTA͔ film was formed in approximately 1 h. When the oxygen content was lowered below 15 ppm, an insulating film could not be obtained in 4 h, clearly showing that the formation of the inhibiting ͓Cu͑I͒-BTA͔ requires oxygen.

The formation of inhibitive benzotriazole films on copper and copper alloyed with silver has been studied with scanning electrochemical microscopy ͑SECM͒ and X-ray photoelectron spectroscopy ͑XPS͒. The SECM measurements showed that the film grows rapidly on oxygen-free dehydrated copper ͑OF-HC͒ and that the rate depends on the substrate potential. The benzotriazole films were also observed on silver alloyed copper; however, electropolishing prevents film growth by enriching the surface with silver. XPS results show that the film consisted of ͓Cu͑I͒-BTA͔ on both materials. No evidence of ͓Ag͑I͒-BTA͔ was found.