Effect of additives on Cu electrodeposits: electrochemical study coupled with EQCM measurements

Abstract

The effect of polyethylene glycol (PEG) and chloride ions on Cu electrodeposition mechanism is investigated. Using blank electrolyte, electrochemical measurements show that PEG adsorbs more or less on the electrode surface depending on the nature of this surface (copper, gold). Alternative current techniques and electrochemical quartz crystal microbalance (EQCM) experiments are performed at open circuit and under polarisation. They show that the PEG adsorption on the Cu electrode is weak at open circuit, but increases under polarisation. In complementary EQCM tests made on Au and on electrodeposited Cu, we conclude that the H 2 gas production reduces the apparent mass of the gold surface. In contrary on Cu, H 2 entrapped in the Cu deposit increases the mass. In all cases, there is an important mass hysteresis. Whatever the substrate, the addition of PEG + Cl − to solution has a beneficial effect by reducing this hysteresis due to the H 2 production. For Cu electrolytes, the PEG addition to solution has little effect, while the simultaneous PEG + Cl − addition inhibits both the Cu 2+ reduction current and the mass increase. Atomic force microscopy (AFM) images made on the deposits confirm the beneficial effect of the two additives in solution.

Electrochemical Analysis of H[sub 2]O[sub 2] and Nitrite Using Copper Nanoparticles/Poly(o-phenylenediamine) Film Modified Glassy Carbon Electrode

“…40 However, the cathodic current increased up to Ϫ1.7 V because of the hydrogen evolution reaction at higher cathodic peak potential. 50,51 This observation was supported by earlier reports, 50,51 and they found that a continuous mass increase is observed as the potential is scanned in the cathodic direction during the deposition of Cu-NPs. After the frequency change during the potential scanning from Ϫ0.4 to Ϫ1.7 V, the amount of Cu NPs deposited on the PoPD film was estimated to be +422 ng.…”

Shape Control of Electrodeposited Copper Films and Nanostructures through Additive Effects

“…The parameters from both the area roughness and grain size analysis show that the roughness of Cu films from electrolyte solutions containing MG is greater than 5 times smaller than that of Cu films from additive-free solutions. Similar leveling and brightening effects of additives on Cu electrodeposits have been observed for polyethylene glycol (PEG) + Cl − , and 4,5-dithiaoctane-1,8-disulfonic acid (SPS) + PEG systems, 33,34 but the smoothing effect of MG in this work appears to be more significant than that for PEG + Cl − . 34 3.3.3.…”

Voltammetric Study of the Inhibition Effect of Polyethylene Glycol and Chloride Ions on Copper Deposition

“…These experiments involved scans proceeding from the OCP in the cathodic direction to −0.9 V. All solutions had a base composition of 0. 25 As the solution was added, the working electrode rotation speed was increased to 2000 rpm for a few seconds to homogenize the contents and then reduced back to 500 rpm. The current was monitored during the pause and the scan not resumed until a total time of 10 min had elapsed.…”

“…13,19,22,23 Experimental evidence from several techniques has indicated that little or no PEG adsorbs on copper in the absence of Cl − . 19,[24][25][26][27] The ability of Cl − and PEG to inhibit Cu 2+ reduction is affected by their concentrations, PEG molecular weight, and electrode potential. 8,11,[13][14][15]19,22,23,25,[28][29][30][31][32][33] Inhibition increases with Cl − concentration up to a limit at fixed PEG concentration.…”