ATR FTIR study of levellers for Cu electrodeposition from acidic sulphate solution

AbstractIn the present paper, an in situ attenuated total reflection Fourier transform infrared (ATR FTIR) study of two model levellers for Cu electrochemical plating, i.e. 4-cyanopyridine (4-CP) and 3-diethylamino-7-(4-dimethylaminophenylazo)-5-phenylphenazinium chloride (Janus Green B, JGB) is reported. The working electrode was a Si prism coated with electrolessly plated Au film. The following types of ATR FTIR experiments: (i) potentiostatic measurements with the working electrode pre-electroplated with a thin Cu layer in a KClO4 solution containing the relevant organic; (ii) potentiostatic copper electrodeposition from an acidic CuSO4.5H2O bath containing 4-CP or JGB, were carried out. Spectral features related to unreacted and reacted 4-CP were observed in both experiments with pre-electrodeposited Cu and during electrodeposition. Furthermore, reorientation of adsorbed 4-CP was highlighted. As far as JGB is concerned, the main peaks observed with both pre-electroplated and growing Cu electrodes indi...