Electropolishing of Copper in H[sub 3]PO[sub 4]

Electropolishing copper in was studied using both ex situ and in situ optical techniques. First, an ex situ study revealed the influence of the electropolishing potential on the visual appearance and the surface topography. Gloss together with total integrated scattering reflected the changes in surface roughness as evidenced from optical profilometry images. Second, an in situ optical study using ellipsometry revealed the changes in the thickness of the surface film, as well as roughness modifications. Altogether, this provided the characterization of the whole electropolishing process in terms of roughness and film formation. From the polarization curve combined with the complementary analysis techniques it was observed in situ that an initial regime showed increased roughness of the copper surface, followed by a current limiting plateau exhibiting the best conditions of electropolishing: anodic brightening. For higher applied potentials, a region with pitting and deterioration of the appearance followed.