COPPER DEPOSITION IN THE PRESENCE OF POLYETHYLENE-GLYCOL - I - QUARTZ-CRYSTAL MICROBALANCE STUDY

The addition of polyethylene glycol (PEG) and Cl- to an acid copper el ectrolyte inhibits the deposition reaction for cathodic overpotentials of up to about 150 mV. Adding Cl- only promotes the deposition reacti on, while adding PEG alone has a relatively small effect on electrode kinetics. Frequency shifts of an electrochemical quartz crystal microb alance suggest the adsorption of a monolayer of PEG molecules that are collapsed into spheres provided chloride ions are present, with littl e adsorption occurring when Cl- is absent. This behavior is the same f or gold and copper surfaces. Transient current measurements suggest th at chloride ions affect the PEG adsorption equilibrium rather than ads orption kinetics alone.