In Situ Observations of Shape Evolution during Copper Dissolution Using Atomic Force Microscopy

Abstract

Atomic force microscopy was used to monitor, in situ, the shape evolution of polycrystalline copper during anodic dissolution in 0.5M H2SO4. During dissolution of the copper surface under a small anodic potential (30 mV), an overlayer of material that resulted from mechanical polishing was removed, exposing the underlying grain boundaries. A chemically etched sample was exposed to the same experimental conditions, and no overlayer was observed. Dissolution of the copper bulk metal was monitored under a higher applied potential (100 mV, 0.5M H2SO4). The overlayer was immediately removed, and the dissolution produced a nonuniform, crystallographically-etched surface. The inhibiting effect of benzotriazole (BTA) on copper dissolution in 0.5M H2SO4/20 mM BTA was observed. Copper dissolution did not proceed at 100 mV or 200 mV applied potential; but at 300 mV, rapid localized dissolution resulted in the formation of pit-like features.