Electrodeposition of Cu from Acidic Sulphate Solutions in the Presence of PEG: An Electrochemical and Spectroelectrochemical Investigation – Part I

Abstract

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.

Experimental Design and Response Surface Analysis as Available Tools for Statistical Modeling and Optimization of Electrodeposition Processes

“…For example, Healy & Pletcher (1998a, 1998b have shown that the studied additives (Cl -, polyethylene glycol, and 4,5-dithiaoctane-l,8-disulfonic acid) adsorbed on the electrode at different deposition potentials and stirring speeds influences in the copper reduction mechanism. Similar results were observed by Bozzini et al (2006) and Tantavichet & Pritzker (2006), who studied the effects of polyethylene glycol and benzotriazole, respectively. Nayana et al (2011) have investigated the influence of additives on the morphology and brightness of nanocrystalline zinc electrodeposited from an acid sulfate bath.…”

Electrodeposition of Cu from Acidic Sulphate Solutions in the Presence of PEG - Part II Visible Electroreflectance Spectroscopy Measurements during Electrodeposition

“…Within a given bath, the differences in trends can be explained in terms of the wavelength-dependence of the maxima and minima of the r(f) curves. Between baths, one can observe that the differences in behaviour between the solutions without and with PEG can be described in terms of lower f values for the latter system: this can correlate to the higher growth stability observed in the presence of the additive [1].…”

“…In the first part of this series [1], we reported an electrochemical, Surface-enhanced Raman Spectroscopy (SERS) and Scanning Electron Microscopy (SEM) investigation of the effects of PEG. This paper focuses on in situ purely optical component of the absolute instantaneous reflectivity f volume fraction of metallic particles g 1 purely geometrical factor weighting reflectance g 2 wavelength-dependent geometrical factor weighting reflectance i imaginary unit Im(Z) imaginary part of a complex number Z R(k,t) absolute instanteous spectral reflectance Re(Z) real part of a complex number Z t time…”

“…relative instantaneous reflectance Dk model parameter describing the frequencywidth of the interband-transition region of the spectral reflectivity of coinage metals and alloys e complex dielectric function e B dielectric function of bound electrons e c dielectric function of the composite film e e dielectric function of the electrolyte e EM dielectric function of the embedding medium e F dielectric function of free electrons e m dielectric function of the bulk metal k wavelength k IB interband transition wavelength k n plasma wavelength of free electrons k ref reference wavelength k 1,2 wavelengths set as fixed during ER experiments q(t) roughness at time t r relative instantaneous reflectivity electroreflectance measurements, relating them to the effects of PEG on electrocrystallisation processes occurring during potentiostatic electrodeposition. Electroreflectance Spectroscopy (ERS) data are complemented by SEM and are correlated with the potential-dependent surface-enhancement derived from a quantitative analysis of the SERS spectra reported in Part I of this paper [1].…”

“…Electroreflectance Spectroscopy (ERS) data are complemented by SEM and are correlated with the potential-dependent surface-enhancement derived from a quantitative analysis of the SERS spectra reported in Part I of this paper [1].…”