SURFACE DEVELOPMENT DURING ELECTROLESS COPPER DEPOSITION

We report on the electroless copper deposition with formaldehyde as th e reducing agent. The reaction occurs in highly alkaline solutions. Si nce copper ions are present as EDTA complexes, a catalyst is needed to facilitate copper ion reduction. Methanediolate anions, intermediates of the formaldehyde oxidation, act as such a catalyst. Furthermore, f reshly deposited copper exhibits increased catalytic activity toward f ormaldehyde oxidation. Both effects lead to strong coupling between th e anodic and cathodic partial processes. Such a feedback can lead to o scillatory behavior of the deposition reaction. In this work we use sc anning tunneling microscopy to study the deposition rate with high spa tial resolution. We could establish that the deposition rate fluctuate s locally and with time.