In this paper we report on the reactivity of adsorbed cyanide deriving from ligand release during metal electrodeposition from cyanocomplex solutions of Au(I), Au(III), Ag(I) and Cu(I) in H 2 O and D 2 O. When CN¯ is adsorbed at cathodic potentials in excess of the HER threshold, metal-dependent reactivity can be detected by SERS. Finite surface coverages with adsorbed CN¯ at such cathodic potentials can be obtained only if CN¯ is delivered directly to the cathode surface as by decomplexing of the cyanocomplexes of the metals undergoing cathodic reduction. In Au(I) and Au(III) baths, Au-CN¯ reacts with Au-H• and is hydrogenated to adsorbed CH 2 =NH and CH 3 -NH 2 .In Ag(I) baths, Ag-CN¯ reacts with Ag-H • giving rise to polycyanogens. No reactivity of Cu-CN¯ was found, under otherwise identical conditions. Our conclusions are supported also by dedicated DFT molecular computations.
A technique has been developed for the study of reaction mechanism and the monitoring of copper electroplating baths utilizing a combination of solid phase extraction ͑SPE͒ and high-performance liquid chromatography ͑HPLC͒. This method appears suitable for live plating bath control as well as for organic identification, concentration measurement, and reaction mechanism studies. While in the past the total amount of carbon ͑TOC͒ present in the deposition bath was used to quantify the decomposition of organics and to determine the plating bath quality, a strong correlation between the TOC measurement and effective plating bath composition was not possible. Moreover, a direct way to thoroughly analyze the organic components of the bath is not commonly available using current electrochemical techniques. However, the results from experiments conducted with the technique described in this paper show how the monitoring of a few diagnostic peaks recovered from a live bath sample can be used directly for this purpose. The identification and quantification of by-products is also proven. Two copper sulfuric plating baths at different acidity were used for this study, and the stability of bis͑sodiumsulfopropyl͒ disulfide and polyethylene glycol additive components, as well as their degradation mechanism and by-products, are studied in this work.
This paper reports an in situ Raman study of Cu electrodeposition from an acidic sulfate solution in the presence of bis-͑3-sulfopropyl͒-disulfide Na salt ͑SPS͒. In the absence of chloride, in situ surface-enhanced Raman spectra scarcely show few labile features in a narrow range of cathodic potential. When Cl − ions are added to the deposition bath, several features are clearly visible in the spectra, showing that SPS is adsorbed on the copper surface in a wide potential window during Cu electroplating.
This paper deals with the effects of PEG during Cu electrodeposition from an acidic sulphate solution. This investigation was carried out with electrochemical and spectroelectrochemical techniques. Potentiostatically grown layers were examined by scanning electron microscopy. Adsorption of PEG on the growing Cu surface can be inferred from electrokinetic, SERS and morphological evidence: variations of the estimated exchange current density, qualitative and quantitative differences in the potentiostatic transients, changes on the cathodic current efficiency, effects on the three-dimensional crystallisation mode under both compact and dendritic growth conditions, appearance of surface-enhanced PEG-related Raman bands. SERS spectra revealed cathodic reactivity of adsorbed PEG.
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