Copper electrodeposition from an acidic plating bath containing accelerating and inhibiting organic additives

Copper electrodeposition on copper from still plating solutions of different compositions was investigated utilising electrochemical impedance spectroscopy (EIS), cyclic voltammetry, and scanning electron microscopy (SEM). An acid copper sulphate plating base solution was employed either with or without sodium chloride in the presence of a single additive, either polyethylene glycol (PEG) or 3-mercapto-2-propanesulphonic acid (MPSA), and their mixture. Thallium underpotential deposition/anodic stripping was employed to determine the adsorption capability of additives on copper. In the absence of chloride ions, MPSA shows a moderate adsorption on copper, whereas PEG is slightly adsorbed. At low cathodic overpotentials, the simultaneous presence of MPSA and chloride ions accelerates copper electrodeposition through the formation of an MPSA-chloride ion complex in the solution, particularly for about 220 μM sodium chloride. The reverse effect occurs in PEG-sodium chloride plating solutions. In this case, from EIS data the formation of a film that interferes with copper electrodeposition can be inferred. At higher cathodic overpotentials, when copper electrodeposition is under mass transport control, the cathode coverage by a PEG-copper chloride-mediated film becomes either partially or completely detached as the concentration of chloride ions at the negatively charged copper surface diminishes. The copper cathode grain topography at the μm scale depends on the cathodic overpotential, plating solution composition and average current density. Available data about the solution constituents and their adsorption on copper make it possible to propose a likely complex mechanism to understand copper electrodeposition from these media, including the accelerating effect of MPSA and the dynamics of PEG-copper chloride complex adsorbate interfering with the surface mobility of depositing copper ad-ions/ad-atoms.     

Kinetics of Sn electrodeposition from Sn(II)–citrate solutions

The influence of solution chemistry on the electrodeposition of Sn from Sn(II)–citrate solutions is studied. The distribution of various Sn(II)–citrate complexes and citrate ligands is calculated and the results presented as speciation diagrams. At a SnCl₂·H₂O concentration of 0.22 mol/L and citrate concentration from 0.30 mol/L to 0.66 mol/L, SnH₃L⁺ (where L represents the tetravalent citrate ligand) is the main species at pH below about 1.2 and SnHL⁻ is the main species at pH above about 4. Polarization studies and reduction potential calculations show that the Sn(II)–citrate complexes have similar reduction potentials at a given solution composition and pH. However, the Sn(II)–citrate complexes become more difficult to reduce with higher total citrate concentration and higher solution pH. Nevertheless, SnHL⁻ which forms at higher pH is a favored Sn(II)–citrate complex for Sn electrodeposition due to better plated film morphology, likely as a result of its slower electroplating kinetics. Precipitates are formed from the Sn(II)–citrate solutions after adding hydrochloric acid (to lower the pH). Compositional and structural analyses indicate that the precipitates may have the formula Sn₂L.     

Influence of polyethoxylated additives on zinc electrodeposition from acidic solutions

The influence of several ethoxylated additives (ethyleneglycol and polyethyleneglycol polymers of different molecular weights) on the nucleation, growth mechanism and morphology of zinc electrodeposited from an acidic chloride bath is reported. The electrochemical study was carried out using cyclic voltammetry, inversion potential and chronoamperometric techniques. The dimensionless graphs model was applied to analyse the nucleation process and the results showed that the studied additives have a blocking effect on the electrodeposition of zinc. This effect occurs in the first stages of the nucleation process and is dependent on the molecular weight of the additive. Changes induced by the presence of additives in the morphology and grain size of the deposits were observed using SEM analysis. Results show that the presence of additives modifies the nucleation process and determines the final properties of the deposits.     

Effects of organic additives on zinc electrodeposition from alkaline electrolytes

This work reports the effects of four organic compounds (referred to as levelers) on the electrodeposition of Zn on steel from alkaline free-cyanide electrolytes. The additives tested included polyvinylalcohol (PVA) and the condensation products of epichlorhydrin with amines, called polyamines (PAs), that were synthesized using an aliphatic amine (PA-I, from diethylamine and PA-II from diethylamine-triethylamine), and a heterocyclic quaternary imidazolium molecule (PA-Imid, from imidazole). These compounds were evaluated in the absence and in addition to a quaternary ammonium brightener, N-benzyl-3-carboxylpyridinium chloride (3NCP). The imidazole derivative-based polyamine (PA-Imid) causes greater inhibition of the zinc reduction process than the aliphatic polyamine, and more cathodic overpotential is necessary to promote massive metal deposition. The morphology of the deposits is modified when polyamines are added to the bath; more compact and smaller crystals are obtained with PVA as well as with polyamine PA-I. The addition of PA-II as well as PA-Imid yields crystals growing perpendicular to the substrate. The addition of 3NCP with PVA, PA, or PA-Imid increased the deposition overpotential and modified the morphology by diminishing the grain size. In the absence of additives, crystallographic orientation favored the basal Zn(002) with high atomic packing. The addition of the levelers favored the high-angle pyramidal Zn(101) with low atomic packing. The combination of the levelers with (3NCP) favored the prismatic Zn(100) crystallographic orientation. Additives decrease the size of zinc crystals and tend to increase the energy of lattice favoring the growth of pyramidal and prismatic planes.     

Influence of additives on the electrodeposition of nickel from a Watts bath: a cyclic voltammetric study

The electrochemical reactions occurring during the deposition of nickel from a Watts bath have been examined using a voltammetric technique. The important reactions taking place at the anode and cathode have been systematically identified. The influence of the additives on the cathodic and anodic reactions show the importance of careful bath preparation for a quality controlled product. From the surface coverage data, the free energy change (G _a ⁰ ) for the adsorption of the brighteners has been calculated and compared with results from methods used earlier.     

Effect of additives on electrodeposition of tin and its structural and corrosion behaviour

The present investigation deals with the electrodeposition of tin from chloride electrolytes. Gelatin, β-naphthol, polyethylene glycol, peptone and histidine were used as additives in the plating bath to improve the surface morphology, grain size, smoothness and corrosion resistance of the tin deposits. XRD data obtained for electrodeposited tin show polycrystalline nature with single β-phase and tetragonal structure. A uniform and pore free surface was observed under SEM analysis. AFM results indicate the grain refining brought about by the additives. Corrosion rate measurements using the Tafel extrapolation method and electrochemical impedance spectroscopy reveal the increased corrosion resistance from baths containing additives.     

指甲花萃取物对镍从瓦特镀液中电沉积的影响(英文)

采用赫尔槽试验、分散能力测定法、扫描电镜、X射线衍射、能谱分析、硬度测量及交流阻抗谱,研究指甲花萃取物(主要成分为2-羟基-1,4-萘醌)对镍从瓦特镀液中电沉积(以低碳钢为基体)的影响。在温度40~50°C和pH4.5~5.0的条件下,从含60mL/L指甲花萃取物的瓦特镀镍液中得到的镀层具有良好的耐蚀性和硬度。指甲花萃取物作为瓦特镀镍液的添加剂,极大地提高了镀液的分散能力和电流效率。在最佳指甲花萃取物浓度下所得的镀镍层为晶态,结晶细致。     

A novel polymeric leveller for the electrodeposition of copper from acidic sulphate bath: A spectroelectrochemical investigation

The electrodeposition of copper has recently become a “hot topic” due to its extensive application to the fabrication of interconnects in the integrated circuits (IC) manufacturing process. However, the proper composition of the electrochemical deposition (ECD) bath, and in particular the selection of the levelling agent, represents one of the crucial factors for an effective transition of Cu ECD towards the most advanced technology nodes. In this paper we report on the electrodeposition of Cu from acidic sulphate baths containing a potential innovative polymeric leveller: a benzyl-phenyl modified polyethyleneimine (BPPEI). This investigation was carried out by: (i) cyclic voltammetry (CV) at a rotating-disk electrode, (ii) in situ surface-enhanced Raman spectroscopy (SERS) during electrodeposition and (iii) scanning electron microscopy (SEM). CV results show that BPPEI acts as an inhibitor of the electrodeposition process, since it reduces the exchange current density and increases the cathodic Tafel slope. Mass transport limitations to the Cu(II) reduction process are essentially unaffected by the presence of BPPEI. SERS spectra show that BPPEI is adsorbed at the growing Cu cathode at all potentials of interest for electroplating. SEM micrographs prove that BPPEI acts as an efficient grain-refiner and suppressor of unstable 3D growth. Cathodic reactivity of BPPEI was proved by the analysis of CV features and potential-dependent SERS spectral changes.     

Study of the influence of the polyalcohol mannitol on zinc electrodeposition from an alkaline bath

In this paper, the effects of adding mannitol to an alkaline plating bath on the electrodeposition of zinc onto AISI 1010 steel are described and assessed. From cyclic voltammograms with various lower-limit potentials, it is concluded that an initial zinc bulk deposition (region of wave c ₀) occurs from −1.45 V in the negative sweep. When the sweep is reversed at −1.60 V, an anodic peak a ₁ is seen in the positive sweep both in the absence and in presence of mannitol, which was assigned to zinc dissolution. This peak indicates that the primary nucleation and growth of zinc in region c ₀ is followed by zinc secondary nucleation and growth (region of peak c ₁). Scanning electron micrographs show that zinc electrodeposits obtained at mannitol concentrations ≥0.10 M were more refined than at lower concentrations. Energy-dispersive X-ray spectroscopy of these electrodeposits show oxygen contents that are generally low or below detection limit.     

电沉积条件对甲基磺酸锡镀层织构的影响

为了在实际应用中控制甲基磺酸电镀锡镀层的织构以提高镀层性能,采用X-射线衍射分析方法研究了镀锡工艺中表面活性剂浓度、电流密度和镀层厚度对镀锡层织构的影响规律,XRD分析结果显示,表面活性剂聚乙二醇辛基苯基醚(OP)浓度高,镀层以(211)和(321)晶面择优;OP浓度低,镀层以(101)和(112)晶面择优低电流密度有利于镀层以(211)和(312)晶面择优,高电流密度则有利于(101)和(112)晶面择优;镀层较薄时没有明显的晶面择优,(211)晶面的衍射峰强度随着镀层厚度的增加而加大,当镀层厚度超过10μm镀层以(211)和(321)晶面的衍射峰为主,且基本不随镀层厚度的增加而变化.由于晶态基底会影响镀锡层的织构和形貌,本甲基磺酸镀锡工艺以多晶紫铜化学镀非晶态镍磷合金为阴极,对非晶态基底上得到的锡镀层进行研究。     

Studies on the electrodeposition of nickel from a Wattss' bath in the presence of sodium naphthalene-2-sulphonate and acrylamide additives

It has been possible to obtain very bright, smooth electrodeposits of nickel from a Watts' bath using a combination of sodium naphthalene-2-sulphonate and acrylamide additives. The electroplates obtained in the presence of sodium naphthalene-2-sulphonate alone and those in the presence of a combination with acrylamide have been examined for their surface roughness, surface topography, sulphur content and various other properties. The results show that the additives modify the structure and surface topography of the deposits to a large extent while producing smooth deposits without a preferred orientation.     

Reliability improvement of conductive adhesives on tin (Sn) surfaces

Effective organic corrosion inhibitors are introduced into a typical electrically conductive adhesive (ECA) formulation and evaluated. With the incorporation of small amounts of these additives, lower bulk resistivity and highly stable contact resistance on tin (Sn) surfaces were achieved. Contact angle, grazing angle Fourier Transfer Infrared (FT-IR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS) characterizations showed the presence of coatings of the corrosion inhibitors on the metal surfaces. A barrier passivation layer formed on Sn surfaces with the effective corrosion inhibitors. X-ray diffraction analysis confirmed that such a passivation layer protected the Sn surface and prevented oxidation and corrosion under elevated temperature and humidity environment.     

Influence of tartaric acid on zinc electrodeposition from sulphate bath

The effect of tartaric acid on zinc electrodeposition from sulphate plating bath was investigated by electrochemical impedance spectroscopy (EIS), stationary polarization curves, X-ray diffraction and SEM imagery. The study shows that it is possible to obtain homogeneous, compact and dendrites-free zinc deposits from sulphate solutions containing tartaric acid. For various hydrodynamic methods (rotating disc electrode and static vertical or horizontal electrode), the results indicate that, the presence of only small quantity of tartaric acid, may induce significant changes on deposition rates and deposit quality.     

Influence of bath temperature and bath composition on Co-Ag electrodeposition

A study of the best conditions to prepare smooth heterogeneous Co-Ag films with low amounts of S from a thiourea-based electrolytic bath has been performed. Using a 0.01 M AgClO₄ + 0.1 M Co(ClO₄)₂ + 0.1 M thiourea + 0.1 M sodium gluconate + 0.3 M H₃BO₃ + 0.1 M NaClO₄ bath, low temperature (10 °C) allowed obtaining compact and smooth deposits containing 2 wt.% sulphur. Decreasing thiourea content 0.06 M and increasing gluconate concentration up to 0.3 M, better deposits (more compact with lower sulphur content (1.2 wt.%)) were obtained. A clear influence of the species present in the bath on the film quality was observed: while gluconate favoured film cohesion, boric acid hindered hydrogen adsorption. For all films, fcc-Ag, hcp-Co and hcp-CoAg₃ phases were always detected by XRD, TEM and electron diffraction, their proportions varying with the electrodeposition conditions. Magnetic measurements revealed that the increase in the CoAg₃ led to an increase in the film coercivity. GMR values were only measured at cryogenic temperatures, they being higher for the deposits with the lowest sulphur content revealing that sulphur exerts a negative effect on magnetoresistance.     

Model of nickel electrodeposition from acidic medium

A step-wise computer model is presented for simultaneous deposition of nickel and nickel hydroxide in aqueous solutions. In acidic solutions ({pH} 1), the potentiostatic current-time transient response on glassy carbon or titanium was analysed with respect to nucleation and radial growth mechanism. pH changes influence the current-time response greatly. A marked maximum in the current transient appears for slightly acidic solutions ({pH} 4.5) and a consecutive decrease in the deposition current density at long times is obtained. This behaviour is attributed to early precipitation of nickel hydroxide due to a local pH increase at the cathode surface.     

Pulsed electrodeposition of microcrystalline chromium from trivalent Cr-DMF bath

Pulsed electrodeposition (PED) with square wave has successfully been applied to deposit microcrystalline chromium from Cr-dimethylformamide (DMF) bath. The influence of the duty cycle, on-time, off-time, frequency, and pulse peak current on thickness, current efficiency, and hardness were investigated. Based on the analysis of the microstructure, the corrosion behavior of both direct-current deposited (DCD) and pulse-current deposited (PED) chromium in 3.5% NaCl solution was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results indicated that both pulsed electrodeposits and direct-current deposits have high charge transfer resistance R _ct and very low I _corr compared with mild-steel substrate.     

酸性锌镍合金电镀工艺参数对镀层镍含量的影响

研究了采用弱酸性氯化物体系电镀锌镍合金时镀液的镍锌比、温度、氯化铵含量,以及阴极电流密度、电镀方式等工艺参数对镀层镍含量的影响.结果表明,镀液镍锌比、温度、阴极电流密度对镀层镍含量影响较明显,氯化铵含量及磁力搅拌对镀层镍含量几乎无影响,采用脉冲电镀可以显著提高镀层镍含量.     

Electrochemical and AFM study of Zn electrodeposition in the presence of benzylideneacetone in a chloride-based acidic bath

The influence of benzylideneacetone (BDA) on the mechanism of zinc deposition and nucleation was studied by voltammetry, chronoamperometry and atomic force microscopy (AFM). The addition of BDA to the electrolyte solution partially inhibited (97%) the reduction of zinc at the potential E = –1.15 vs SCE/V, giving rise to an increase in the overpotential for the discharge of the metal ion. This leads to the existence of two reduction processes with different energies that involve the same species, ZnCl₄ ^2-. Analysis of chronoamperograms obtained in the absence and presence of BDA indicates that distinct nucleation mechanisms are involved during the initial stages of Zn deposition. In the absence of BDA, the transients are consistent with the model of 3D diffusion-controlled nucleation. In the presence of BDA, the transients exhibit a more complex form involving two growth processes. The first process, which occurs at short times, is explained in terms of a combination of three simultaneous nucleation processes: 2D progressive, 2D instantaneous, and 3D progressive nucleation, each limited by the incorporation of adatoms. The second process, which occurs at longer times, involves the three processes that occur at short times in conjunction with a principal contribution from a diffusion-controlled 3D nucleation mechanism. AFM imaging shows that the morphology of the deposited zinc depends on the applied electrode potential.     

Cathodic electrodeposition of Y(OH)3 and Y2O3 nanostructures from chloride bath. Part II: Effect of the bath temperature on the crystal structure,composition and morphology

Ultra-fine nanoparticles, mono-dispersed nanospheres and nanorods of Y(OH)₃ and Y₂O₃ were successfully prepared via electrodeposition from chloride bath at different temperatures of 10, 25, 40 and 80 °C followed by heat-treatments at 600 °C in dry air atmosphere. Thermal behavior of the hydroxide samples was investigated by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The structural and morphological characteristics of the products were determined by X-ray diffraction (XRD), FT-IR, scanning and transmission electron microscopy (SEM and TEM). Effects of bath temperature on the mechanism of base electrogeneration and deposit formation on the cathode surface were proposed and discussed. The results showed that the crystal structure, composition and morphology of the products are mainly affected by the temperature of electrodeposition bath.     

添加剂对无氰电镀铜-锡合金(低锡)镀层性能的影响

通过赫尔槽试验与直流电解试验,研究了添加剂在焦磷酸盐溶液体系无氰电镀铜-锡合金(低锡)工艺中的作用.该体系镀液组成与工艺条件为:Cu2P2O7·3H2O 25 g/L,Sn2P2O7 1.0 g/L,K4P2O7·3H2O 250 g/L,K2HPO4·3H2O 60 g/L,温度25℃,pH 8.5,电流密度1.0 A/dm2.采用扫描电镜(SEM)、X射线衍射(XRD)、能谱(EDS)、中性盐雾试验等方法研究了添加剂对镀层组成结构、外观、耐腐蚀性能及微观形貌的影响.结果表明,焦磷酸盐溶液体系无氰电镀铜-锡合金(低锡)时使用有机胺类添加剂可抑制Sn的析出,使合金镀层致密均匀,耐蚀性能好.镀层结晶主要为Cu13.7Sn结构,镀层中Sn含量为9％～11％.镀液中添加剂的使用量增加,则合金镀层中的Sn含量降低.