Double zincate pretreatment of sputter-deposited Al films

The characteristics of double zincate pretreatment of thin Al films deposited on glass plates using magnetron sputtering and ion-beam sputtering were investigated. Traces of Zn deposition and immersion potential as well as surface observations using scanning electron microscopy and atomic force microscopy showed that continuous dissolution of an Al film during the double zincate pretreatment occurred in the case of a magnetron sputter deposited film, resulting in Al film failure from the substrate. On the other hand, the substitution reaction of Al dissolution and Zn deposition occurring on the ion-beam sputter-deposited film ceased during the first and the second zincate treatment processes. The difference between the behaviors of the double zincate treatments for the two kinds of sputter-deposited films is related to the film structure. A magnetron sputter-deposited film has a columnar structure, resulting in higher susceptibility to the dissolution reaction in a concentrated alkaline zincate solution. On the other hand, an ion-beam sputter-deposited film has a fine microcrystalline structure with a low density of defects, resulting in lower susceptibility to the dissolution reaction. (C) 2001 The Electrochemical Society.