The mass transfer in Al film during local anodic oxidation investigation

Abstract

Mechanical stresses in aluminium thin films arise during electrochemical oxidation. In this case, there are structural stresses in aluminium films caused by the change of specific volume as a result of aluminium structural transformations into anodic oxide. The mechanical stresses in the thin films can be measured by optical interferometry, X-ray diffraction (Malhorta et al., 1997) or laser scanning (Gardner and Flinn, 1988). However, these methods can be used for measuring mechanical stresses only in the field of elastic deformation. The relative softness of aluminium can result in plastic deformation, and Al film plastic deformation results in mass transfer. The main role in the mass transfer is played by slip and creeping dislocation mechanisms with partial stress relaxation (Koleshko et al., 1987; Marieb et al., 1994). The plastic deformation in Al films can be measured by an X-ray method, but usage of this X-ray method does not yield complete representation of the mass transfer as a result of plastic deformation in the film. The main goal of this paper was examination of mass transfer in aluminium films during local area anodization. The plastic deformation arises due to an edge effect of lateral anodization of aluminium under a mask (Surganov and Mozalev, 1997).