Kinetics Of Copper Deposition Research Articles

Peculiarities of Electroless Copper Deposition Using Environmentally-Friendly Natural Polyhydroxylic Compounds As Cu(II) Ligands

Cu(II) ligands are important components of common formaldehyde-containing alkaline electroless copper plating baths:Cu(II)-Ligand + 2CH2O(hydrated) + 4OH- → Cu + 2HCOO- + H2 + 2H2O + Ligand (1)From one hand, the ligands used should form Cu(II) complexes stable enough to prevent Cu(OH)2 formation, since the solubility product of Cu(OH)2 is of the order 10-18 and the concentration of “free” (uncomplexed) Cu(II) ions in the pH range 11–14 cannot exceed 10-12–10-18 M, respectively. On the other hand, it is worth to note that kinetics of copper deposition as well as the properties of copper deposits (compactness, exterior, morphology and crystal structure) in high extent depend on the nature of ligands used for Cu(II) binding into complexes in electroless copper plating solutions.The aim of the study presented herein was comparison of the parameters of process of electroless copper plating – mainly plating rate and nanoscale surface roughness of the copper deposits obtained, – using different polyhydroxylic ligands under the similar conditions.The ligands considered were glycerol, xylitol, D-mannitol, D-sorbitol and saccharose. Acknowledgement The work was carried out within the Project VP1-3.1 ŠMM-08-K-01-009 that is partly supported by the National Programme “An Improvement of the Skills of Researchers” launched by the Lithuanian Ministry of Education and Science.

Kinetic and hydrodynamic implications of 1-D and 2-D models for copper electrodeposition under mixed kinetic-mass transfer control

Numerical analysis of the hydrodynamics and kinetics of copper deposition on a copper rotating disk electrode during voltammetry at a scan rate of 100mVs−1 is conducted to determine the impact of fitting for the system parameters using a 1-dimensional model when the process operates under transition (1000rpm) and turbulent (1500rpm) velocity flow conditions. The 1-dimensional model is based on solution of the transient mass transport equation for Cu(II) utilizing the well-known series solution by von Karman and Cochran for the fluid velocity. The suitability of using this model is assessed by comparison to an axially symmetric 2-dimensional model of the system. In the 2-dimensional model, the Reynolds-averaged Navier–Stokes (RANS) equations are solved first for the pressure and the fluid velocity components which are then used in the transient mass transport equation. The turbulent viscosity is estimated using the k–ɛ model. In both models, transport of Cu(II) by diffusion and convection is coupled to the flux associated with its reduction at the cathode surface. The velocity obtained from the 1-dimensional model is found to be accurate only at locations within a distance of ∼1.4×10−5m from the electrode. Although no significant differences are found for the fitted kinetic parameters obtained using the two models, the diffusion coefficient of Cu(II) fitted using the 1-dimensional model exceeds that obtained from the 2-dimensional model by approximately 44%. The model with the fitted parameters can accurately predict the experimental behavior at a different CuSO4 concentration, although larger deviations arise when the scan rate is reduced to 5mVs−1.

Kinetics of copper deposition on Pt(1 1 1) and Au(1 1 1) electrodes in solutions of different acidities

Kinetics and mechanism of underpotential (UPD) and overpotential Cu deposition (OPD) on Pt(1 1 1), Pt(7 7 5) and Au(1 1 1) electrodes in sulfate solutions of different acidities (pH 0.3–3.7) are studied. In weakly acid solutions, the rates of both Cu UPD and OPD processes are higher as compared with acid solution of copper sulfate (pH 0.3) due to the enhanced concentration of active centers (copper oxides Cu x O) for 2-D and 3-D phase transitions and accelerated discharge of copper ions. The maximum rate of (√3 × √3) R 30° formation is observed at pH 2.7–3.0. At pH > 3.0, the platinum surface is partially blocked by strongly adsorbed oxygen-containing species. At pH < 2.7, the inhibition of Cu UPD and the adlayer desorption are due to the decrease in the charge transfer rate and concentration of copper oxides, which are the defects of adlayer. An optimal, not too high, concentration of adsorbed oxygen-containing species is necessary for ensuring the maximum rate of Cu UPD on platinum. Acidity of electrolytes affects considerably the rate of Cu deposition on Pt(1 1 1) but has only a slight influence on the kinetics of Cu UPD on Au(1 1 1) electrode due to the weaker adsorption of OH − ions on gold. However, the increase in pH accelerates bulk Cu deposition on Au(1 1 1). Adsorption of sulfate anions and hydroxide ions on a monolayer of copper adatoms and Cu crystallites provides accelerated charge transfer (local electrostatic double layer effects of electronegative species) and probably increases the amount of active centers for 3-D nucleation.

The Influence of Temperature and Concentration on Copper Deposition Kinetics in Supercritical Carbon Dioxide

AbstractThe kinetics of copper deposition by the hydrogen-assisted reduction of bis(2,2,7- trimethyloctane-3,5-dionato)copper in supercritical carbon dioxide was studied as a function of temperature and precursor concentration. The growth rate was found to be as high as 31.5 nm/min. Experiments between 220 °C and 270 °C indicated an apparent activation energy of 51.9 kJ/mol. The deposition kinetics were zero order with respect to precursor at 250 °C and 134 bar and precursor concentrations between 0.016 and 0.38 wt.% in CO2. Zero order kinetics over this large concentration interval likely contributes to the exceptional step coverage obtained from Cu depositions from supercritical fluids.

Electrodeposition of Copper on Silicon from Sulfate Solution

In this paper, we report on the energetics and kinetics of copper deposition on n-type Si(100), Si(111), and miscut Si(111) surfaces from 1 mM solution. Electrochemical impedance spectroscopy showed that the position of the bandedges at the surface is very similar for n-Si(100), n-Si(111), and miscut n-Si(111) surfaces. At more positive potentials, the presence of electrically active surface states was observed. Cyclic voltammetry and current transients showed that copper deposition occurs by progressive nucleation and diffusion-limited growth for the three surfaces, which was confirmed by ex situ atomic force microscopy experiments. The rates for copper nucleation on Si(100) and Si(111) are essentially the same, while miscut Si(111) shows a slightly higher nucleation rate. These results indicate that the energetics and kinetics of copper deposition from acidic sulfate solution on silicon are essentially independent of the silicon surface orientation. © 2001 The Electrochemical Society. All rights reserved.

Copper Electroless Plating at Selected Areas on Aluminum with Pulsed Nd‐YAG Laser

Local deposition of copper on aluminum was attempted by the successive processes of anodizing, laser irradiation, and electroless plating. Aluminum specimens covered with anodic oxide films were immersed in , , and diluted NaOH solutions, and irradiated with a pulsed yttrium aluminum garnet (YAG) laser. The time variation in the rest potential of the specimens was followed during laser irradiation by a potentiometer, and the change of the surface composition by laser irradiation was examined by X‐ray photoelectron spectroscopy (XPS). After the laser irradiation, copper electroless plating was carried out in solutions with or without or thiourea. The rest potential measurements and XPS analysis suggested that Cu particles nucleate at the film‐removed area by laser irradiation in and solutions. A copper layer was obtained at the irradiated area by the subsequent electroless plating, and the copper nuclei acted as catalytic centers at the very initial stage in copper electroless plating. The effects of and thiourea concentration and the deposition temperature on the kinetics of copper deposition is also discussed. © 2000 The Electrochemical Society. All rights reserved.

New Insights into Evaluation of Kinetic Parameters for Potentiostatic Metal Deposition with Underpotential and Overpotential Deposition Processes

Kinetics of copper deposition onto an Au(111) surface from sulfuric acid electrolyte, was evaluated using potentiostatic current transients. Measurements were conducted employing a new and nontradi...

Electrochemical and Spectroscopic Studies of the Influence of Thiourea on Copper Deposition from Acid Sulphate Solution

SummaryThe effect of thiourea (TU, CS(NH2)2) on the charge transfer controlled and mixed controlled kinetics of copper deposition, from an acid sulphate electrolyte, has been studied via steady state current vs. potential curves at a rotating disc electrode. Pure charge transfer data are extracted and thiourea addition is shown to result in a complex relationship between the exchange current density for copper deposition and the additive concentration. This behaviour can be contrasted with that shown by two other additives, benzotriazole (BTA, C6H5N3) and 4,5-dithiaoctane-1,8-disulphonic acid (DTODSA, (HO3SCH2CH2CH2S-)2). Values of the product of mass transport coefficient and active electrode area (kmA) during cupric ion decay studies at a rotating cylinder electrode have been shown to be dependeht on the electrode potential and on the concentration of TU. Limiting current studies have indicated a potential-dependent adsorption of TU at the electrode surface. In-situ FTIR spectroscopic studies have confirmed the potential-dependent nature of the adsorption of TU at a copper electrode and have also shown that the co-ordination to the metal surface is via the sulphur atom.

Effect of thiourea, benzotriazole and 4,5-dithiaoctane-1,8-disulphonic acid on the kinetics of copper deposition from dilute acid sulphate solutions

The effects of thiourea (TU), benzotriazole (BTA) and 4,5-dithiaoctane-1,8-disulphonic acid (DTODSA) on the deposition of copper from dilute acid sulphate solutions have been studied using potential sweep techniques. Tafel slopes and exchange current densities were determined in the presence and absence of these organic additives. TU and BTA were found to inhibit the copper deposition reaction; increases in the BTA concentration gave a systematic lowering of the exchange current density, whilst TU behaved in a less predictable manner. For BTA and TU concentrations of 10−5 mol dm−3,j0 values of 0.0027 ± 0.0001 and 0.0028 ± 0.0002 mA cm−2 were obtained compared to a value of 0.0083 ± 0.0003 mA cm−2 for the additive free acid sulphate solution. In contrast, in the presence of DTODSA, an increased exchange current of 0.043 ± 0.0003 mA cm−2 was observed. The presence of additives gave rise to measured Tafel slopes of −164, −180 and −190 mV for TU, BTA and DTODSA, respectively, compared to that of −120 mV for copper sulphate alone.

A study of electrochemical kinetics of copper deposition under pulsed current conditions

The investigation is concerned with the drop of current efficiency (CE) of copper deposition under pulsed current conditions. A mathematical model which is based on different charge transfer rates between the following two reactions, $$Cu^{2 + } + e \to Cu^ + $$ (1) and $$Cu^ + + e \to Cu$$ (2) has been formulated to describe the behaviour of a Cu/CuSO4 system under pulsed current conditions on a rotating disc electrode. The results indicate that the CE drops continuously as the difference between the exchange current densities of the two reactions increases. The exchange current densities of Reactions 1 and 2 were estimated to be 0.034 mA cm−2 and 0.024 mA cm−2, respectively. Prediction of CE using the mathematical model agreed to within 3.5% with experimental data over a range 80.4–93.7%.