Adsorption behavior of poly(ethylene glycol) in the presence of two different kinds of halide ions, Br~- and Cl~- revealed using a microfluidic device and a flow cell type electrochemical quartz crystal microbalance

摘要

The adsorption behaviour of poly(ethylene glycol) (PEG) as an additive during Cu electrodeposition was investigated with a microfluidic device and a flow cell type electrochemical quartz crystal microbalance (EQCM). First, the current density (ⅰ) transition curves were measured by using the microfluidic device for rapid exchange from the base electrolyte to electrolytes with added Br and different concentrations of PEG (c_(PEG)) to determine the effective surface coverage ratio (θ_(EFF)) of the electrodes by PEG. Compared with CI~-, the most familiar additive for Cu electrodeposition, Br produced a higher steady-state effective surface coverage ratio (θ_(EFF,SS)) and lower PEG adsorption rate constant (k_a). Finally, the amount of increase in the weight on the electrode (Am) by PEG in a Br/PEG system was measured using an EQCM to calculate θ_(EFF) by Am. The results revealed that the different capability of PEG to suppress ⅰ in the presence of Cl~- and Br~- depends on the Δm.