铜电结晶的研究进展*

铜具有的优良导电性和机械加工性能以及其电沉积工艺的诸多优点,决定了铜电沉积在各行业特别是近年在高新技术中的广泛应用。铜的电结晶过程是铜电沉积的初期阶段,它决定了后续的电沉积过程及最终镀层的结构和性能,因此一直是研究的热点。本文综述了铜电结晶的研究方法、电结晶理论研究的进展,详细讨论了pH值、添加剂、金属离子、基体以及电沉积条件等因素对铜电结晶的机理和成核动力学的影响,并对研究中存在的问题提出了展望。     

Pyranine-induced self-assembly of colloidal structures using poly(allylamine-hydrochloride)

Complexes of dyes and polyelectrolytes have found widespread use in a variety of functional materials and interfaces. Here it is found that upon mixing the anionic dye pyranine and a cationic polyelectrolyte, poly(allylamine-hydrochloride), two different colloidal structures may form. Above a certain concentration of anionic dye, crosslinking of the polyelectrolyte is initiated, and the formation of sheet-like colloidal structures was observed. Addition of hydroxyl ions resulted in the formation of micron-sized spherical colloids. It was also found that the colloidal shape transition was accompanied by a significant red-shift in the fluorescence emission. Combining fluorescence measurements with studies of the particle size with time, it was found that red-shift was related to the crosslinking of the dye and the polyelectrolyte, and was not influenced significantly by the aggregation and particle growth. Further information about the colloidal behavior and stability was obtained by letting droplets dry and follow the kinetics of this process. It was found that the particles collapsed near the contact line and formed a ring deposit, in agreement with previous studies. However, unlike previous studies, the thickness of the ring deposit did not grow significantly with time, due to the peculiar process of formation found here.     

Migration of a colloidal particle in a gradient of electrolyte concentration

When a charged colloidal particle is placed in a solution which is macroscopically nonuniform in electrolyte composition, polarization of the diffuse part of the double layer surrounding the particle propels it through the fluid. In one experiment, gradients of ion concentration in the diffusion boundary layer next to a rapidly dissolving steel panel cause negatively charged latex particles to deposit on the metal at rates comparable to those achieved by electrodeposition. In a second experiment, diffusion of a salt through a filter membrane into a dilute agitated dispersion of latex causes the latex particles to deposit on the filter. Results of both experiments are consistent with a mechanism in which the charged particles migrate with a velocity equal to their electrophoretic velocity in a spontaneously generated electric field having that strength and direction required to prevent an electric current from accompanying diffusion of the ions.     

Electrochemical synthesis of gallium nanowires and macroporous structures in an ionic liquid

The electrochemical synthesis of gallium nanostructures in an ionic liquid is presented. Gallium nanowires and macroporous structures were synthesized by the template-assisted electrodeposition in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py(1,4)]TFSA) containing GaCl(3) as the precursor. Track-etched polycarbonate membranes with an average pore diameter of 90 nm and a thickness of 21 μm were used as templates for the nanowire synthesis. Ga nanowires with a length of more than 4 μm and an average diameter corresponding to that of the template's pores were easily obtained by this method. Macroporous structures with an average pore diameter of 600 nm were obtained by the electrochemical deposition of Ga inside polystyrene colloidal crystal templates and the subsequent removal of the template by THF. The macroporous deposit showed a granular morphology with smallest grain sizes of about 40 nm and light reflections. The nanostructures of Ga were characterized by HR-SEM and EDX analysis.     

Using self-assembled monolayers for controlled electrodeposition of copper into submicrometer size surface features/decrements

This work presents the application of alkanethiols for selectively masking the main surface of copper-seed-layer-covered silicon wafer, as used for the microprocessor production. The target of the investigation was to deposit copper only in the trenches and vias (channels of various shape) of micrometer size and not over the entire surface as in the presently used methods. The procedure developed starts with filling the trenches and vias with water, which is followed by dipping the wafers in a hexane solution containing dissolved dodekanetiol. Alkanetiol adsorbs and self-organizes on copper not protected with water and blocks the electroreduction of copper ions from the bath. The trenches and vias are free from adsorbed alkanetiols due to their very limited solubility in water. The surface-blocking process works very well and may effectively simplify the copper electrodeposition for microelectronic applications. The selective electrodeposition of copper accomplished by the proposed method significantly reduces the problems associated with the removal of excess of copper from the processed circuit elements.     

Optimizing the sputter deposition process of polymers for the Storing Matter technique using PMMA

Quantitative analyses in secondary ion mass spectrometry (SIMS) become possible only if ionization processes are controlled. The Storing Matter technique has been developed to circumvent this so‐called matrix effect, primarily for inorganic samples, but has also been extended to organic samples. For the latter, it has been applied to polystyrene in order to investigate the extent of damage in the polymer, its fragmentation during the sputter deposition process and the effect of the deposition process on the spectra taken by Time‐of‐Flight SIMS (ToF‐SIMS). In this work, a multi‐technique approach, which employs the Storing Matter technique for deposition and ToF‐SIMS and X‐ray photoelectron spectroscopy for characterization, is used to enhance the control of the deposition process, including the thickness of the deposit, the alteration of the source film and the influence of polymer composition on the Storing Matter process. Poly (methyl methacrylate) (PMMA) is used for this work. More detailed information about the sticking of polymer fragments on the metal collector is obtained by density functional theory calculations. This work allows for the conclusion that a part of the fragments deposited on the collector surface diffuses on the latter, reacts and recombines to form larger fragments. The behaviour observed for PMMA is similar to polystyrene, showing that oxygen has no major influence on the processes occurring during the sputter deposition process. Additionally, we have developed a new methodology using 2D ToF‐SIMS images of the deposit to monitor the deposit thickness and to identify surface contaminations. The latter are not only located at the position of the deposit but all over the collector surface. Copyright © 2016 John Wiley & Sons, Ltd.     

High-voltage electrodeposition conditions in the stripping voltammetry of metal ions: A mechanism and analytical prospects of the process

It was found that the exaltation phenomenon in the parallel reduction of hydrogen ions from weak acids or water is responsible for the acceleration of the electrodeposition of metals under high-voltage conditions. Under these conditions, the rate of electrodeposition can be increased by 2 to 3 orders of magnitude compared to the rates of electrodeposition under standard conditions. At a constant high voltage of electrodeposition, the stripping peak currents of metals are proportional to the deposition time and the bulk concentration of analyte ions. Exaltation phenomena can be used in analysis not only for intensifying the process, but also for lowering the limit of detection, improving the selectivity, and decreasing the adverse effect of surfactants. Presented at the V All-Russian Conference with the Participation of CIS Countries on Electrochemical Methods of Analysis (EMA-99), Moscow, December 6–8, 1999.     

Cathodic electrodeposition of ceramic and organoceramic materials. Fundamental aspects

Electrodeposition of ceramic materials can be performed by electrophoretic (EPD) or electrolytic (ELD) deposition. Electrophoretic deposition is achieved via motion of charged particles towards an electrode under an applied electric field. Electrolytic deposition produces colloidal particles in cathodic reactions for subsequent deposition. Various electrochemical strategies and deposition mechanisms have been developed for electrodeposition of ceramic and organoceramic films, and are discussed in the present article. Electrode-position of ceramic and organoceramic materials includes mass transport, accumulation of particles near the electrode and their coagulation to form a cathodic deposit. Various types of interparticle forces that govern colloidal stability in the absence and presence of processing additives are discussed. Novel theoretical contributions towards an interpretation of particle coagulation near the electrode surface are reviewed. Background information is given on the methods of particle charging, stabilization of colloids in aqueous and non-aqueous media, electrophoretic mobility of ceramic particles and polyelectrolytes, and electrode reactions. This review also covers recent developments in the electrodeposition of ceramic and organoceramic materials.     

Ion-exchange properties of colloidal particle consisting of polyaniline and poly(vinyl alcohol) fixed on silica-gel powder.

A colloidal powder was prepared by fixing polyaniline (PANI, conducting polymer), poly(vinyl alcohol) (PVA, surfactant stabilizer) and a suitable dopant anion to silica-gel powder. This hydrophilic composite colloidal particle incorporates anions with the protonation of PANI in an acidic solution. The anion can be exchanged with other anions when the colloid is immersed in an acidic solution. Thus, the PANI colloid works as an ion exchanger. The ion-exchange properties on the composite colloidal powder were investigated. Anions were successfully and easily exchanged in the order Br- < Cl- < NO3- < ClO4- < SCN-. This ion-exchange selectivity corresponds largely to the ion-exchange equilibrium constants, which are based on a hydrophobic interaction between the anion and colloid. However, this ion-exchange selectivity does not agree simply with the lipophilic order, but is instead explainable by a gap in the effective ion-exchange capacity due to a size effect between the micropore on the colloidal particle formed by the dopant anion in polymerization and anion sizes in the hydrophobic environment.     

Electrochemistry of zeolites on thickness shear mode oscillators

This paper describes electrochemical studies of thickness shear mode (TSM) acoustic wave oscillators coated with zeolites. The frequency response of gold on AT-cut 9 MHz quartz oscillators of silver-ion-exchanged zeolite-modified electrodes (ZMEs) under an electrochemical bias is interpreted. This is achieved using a combination of cyclic voltammetry, double-potential-step chronocoulometry (DPSC), and the frequency and resistance responses of the quartz crystal oscillators. Three ZMEs were investigated including fully exchanged Ag(12)A plus partially exchanged Ag(6.4)A and Ag(3.5)A. In all cases, the frequency response of the quartz crystal nanobalance (QCN) could only be interpreted when motional resistance changes were considered. This determines the importance of energy storage and energy dissipation of the shear wave produced by the oscillator in the zeolite film, which was affected by the deposition of silver at the zeolite-electrode-solution interface. The silver deposit formed via the reduction of silver ions originally within the zeolite phase mechanically couples the zeolite film to the underlying substrate. The resistance changes occurring during redox are thus linked to an inner interfacial slip between the zeolite film and the underlying oscillating surface. The data presented are consistent with an extrazeolite redox mechanism.     

Investigations into the electroreduction of copper(II) ions on chalcocite in ammonia solutions using the rotating disc electrode method

Investigations into the electroreduction of copper(II) ions in ammonia solutions on a disc electrode made of synthetic chalcocite having a deficiency of copper atoms have been presented. It has been concluded that within the range of the diffusion controlled process copper(II) ions are the diffusing substance, at the same time in the course of the reaction two electrons are exchanged. The kinetic parameters for the electroactivating process have been estimated. With a higher concentration of copper in solution an inhibition process has been observed, probably caused by a slow transport rate of the species in the material of the electrode. In the system studied the phenomenon of a partially blocked electrode surface does not occur according to the Landsberg model.     

Activation/Inhibition Effects during the Coelectrodeposition of PtAg Nanoparticles: Application for ORR in Alkaline Media

PtAg bimetallic nanoparticles for oxygen reduction reaction (ORR) in alkaline media were prepared by pulse electrodeposition (PED). During PED the reduction of Ag⁺ ions predominates, thus an increased Ag content in the co‐deposit is accomplished. The mechanism for this anomalous co‐deposition was elucidated by potential pulse experiments, which revealed that nuclei formation mainly occurs via the reduction of Pt²⁺ ions. The growth of the particles is diffusion controlled leading to the formation of a Ag shell covering a PtAg alloyed region. However, the shell is not growing homogeneously on the PtAg alloy. Hence, regions of the PtAg alloy are exposed, which exhibit an enhanced ORR activity compared to a pure Ag surface.     

高择优取向Cu电沉积层的XRD研究

采用电化学和XRD方法在CuSO4 +H2 SO4 电解液中获得Cu电沉积层并研究其结构 .结果表明 ,在 4 .0A/dm2 和 15 .0A/dm2 电流密度下可分别获得 (2 2 0 )和 (111)晶面高择优取向Cu镀层 ;Cu镀层晶面织构度随厚度提高而增大 ,获得 (111)晶面高择优Cu镀层的厚度约是 (2 2 0 )晶面的 7倍 ,说明Cu(2 2 0 )晶面比 (111)晶面是更易保留的晶面 ,且低电流密度下铜的电结晶更容易受电沉积条件控制 ;较高的沉积电流密度有利于晶核的形成 ;Cu镀层存在晶格畸变和晶胞参数的涨大     

SERS at structured palladium and platinum surfaces

Palladium and platinum are important catalytic metals, and it would be highly advantageous to be able to use surface enhanced Raman spectroscopy (SERS) to study reactive species and intermediates on their surfaces. In this paper we describe the use of templated electrodeposition through colloidal templates to produce thin (<1 microm) films of palladium and platinum containing close packed hexagonal arrays of uniform sphere segment voids. We show that, even though these films are not rough, when the appropriate film thickness and sphere diameter are employed these surfaces give stable, reproducible surface enhancements for Raman scattering from molecules adsorbed at the metal surface. We report SERS spectra for benzenethiol adsorbed on the structured palladium and platinum surfaces of different thicknesses and void diameters and show that, for 633 nm radiation, enhancements of 1800 and 550 can be obtained for palladium and platinum, respectively.     

Anodic deposition of lead dioxide at Nafion® covered gold electrode

Anodic electrodeposition of lead dioxide at the bare and Nafion® covered gold electrode was studied by cyclic voltammetry and chronoamperometry. The results showed that Nafion® layer has a favourable effect on the efficiency of the deposition process which was caused by both thermodynamic and kinetic reasons. Electrodeposition process at Nafion® covered gold electrode goes via Pb(III) intermediate species which are stabilized within Nafion® membrane. The final PbO₂ deposit crystallizes in tetragonal β-PbO₂ form.     

薄层电沉积的共轭溶解-沉积行为

在铅的薄层电沉积生长中,铅的枝晶沉积物由于氢气的扰动从阴极断裂.断裂的沉积物片段并非在薄层电解槽中保持不动,而是自发地朝阳极方向快速运动.研究表明,这种奇特的现象是由断裂沉积物两端发生的共轭溶解-沉积反应造成的.本文讨论了这种现象产生的机制.     

金属Al薄膜基微池强制沉积胶体光子晶体的制备

强制沉积法是一种利用自组装原理快速沉积胶体晶体有序阵列的模板方法. 我们利用微机械刻划法加工金属Al薄膜, Al膜厚控制微粒粒径和聚醚砜膜厚控制层数, 成功地制备了用于强制沉积光子晶体的微池装置. 为了检验该微池装置的有效性, 我们分别测试了不同粒径(224, 245和283 nm)单分散聚苯乙烯微球的沉积效果, 并且对其中一种微球(283 nm)进行了不同温度的烘干处理, 检验了烘干温度对该样品表面形貌和光子带隙中心波长的影响. 实验结果表明, 该光子晶体呈面心立方结构, 内部晶格完整, 缺陷较少, 带隙中心波长的实验值与计算值符合得较好. 此外, 烘干处理可以使构成光子晶体的微球发生微观变化, 并导致光子带隙中心波长的蓝移.     

Synthesis of Various Metal/TiO2 Core/shell Nanorod Arrays

We present a general approach to fabricate metal/TiO₂ core/shell nanorod structures by two-step electrodeposition. Firstly, TiO₂ nanotubes with uniform wall thickness are prepared in anodic aluminum oxide (AAO) membranes by electrodeposition. The wall thickness of thenanotubes could be easily controlled by modulating the deposition time, and their outer diameter and length are only limited by the channel diameter and the thickness of the AAO membranes, respectively. The nanotubes' tops prepared by this method are open, while the bottoms are connected directly with the Au film at the back of the AAO membranes. Secondly, Pd, Cu, and Fe elements are filled into the TiO₂ nanotubes to form core/shell structures. The core/shell nanorods prepared by this two-step process are high density and free-standing, and their length is dependent on the deposition time.     

Transient natural convection induced by electrodeposition of Li+ ions onto a lithium metal vertical cathode in propylene carbonate

Transient natural convection caused by Li⁺ electrodeposition at constant current along a vertical Li metal cathode immersed in a 0.5 M LiClO₄–PC (propylene carbonate) electrolyte was compared with that by Cu²⁺ ion electrodeposition in aqueous CuSO₄ solution. The concentration profile of the Li⁺ ions was measured in situ by holographic interferometry. The interference fringes start to shift with time at a higher current density. The concentration boundary layer thickness for Li⁺ ions was successfully determined. With the progress of electrodeposition, the density difference between the electrolyte at the cathode surface and the bulk electrolyte increased to induce upward natural convection of the electrolyte. The electrolyte velocity was measured by monitoring the movement of tracer particles. The measured transient behavior of the ionic mass and momentum transfer rates normalized with respect to the steady-state value was numerically analyzed. Transient natural convection along a vertical cathode due to Li metal electrodeposition can be reasonably explained by boundary layer theory, similar to the case of Cu electrodeposition in aqueous CuSO₄ solution.     

Study of electrooxidation of binary electrolytic deposit palladium–bismuth deposited on graphite electrode surface

The phase structure of palladium–bismuth binary electrolytic deposit was studied. The electrodeposition of deposit components on the surface of a graphite electrode (GE) was carried out in situ. On current–voltage curves, the peak of bismuth electrooxidation, the peak of palladium electrooxidation and an additional peak at 0.15 V vs. Ag/AgCl are observed. The peak current at 0.15 V depends both on the concentration of palladium(II) ions and on that of bismuth(III) ions. The thermodynamic theory of alloys in the approximation of the theory of regular solutions was used for calculations. The mixing heat of the binary alloy components and the equilibrium potential of bismuth in the bismuth–palladium alloy are calculated. The calculated equilibrium potential of bismuth in an alloy with palladium is 0.12 V vs. Ag/AgCl which corresponds to the Bi₂Pd intermetallic compound (IMC). Investigation of the surface of a GE with a palladium–bismuth deposit with use of scanning electron microscope showed that the electrolytic deposit contains bismuth, palladium and the Bi₂Pd IMC. Peak at the potential of plus 0.15 V vs. Ag/AgCl is due to selective bismuth electrooxidation from the Bi₂Pd IMC.