Electrodeposition blocking

Fig. 10 Schematic representation of the nanoreplication processes from block copolymers, a Growth of high-density nanowires from a nanoporous block copolymer thin film. An asymmetric PS-fc-PMMA diblock copolymer was aligned to form vertical PMMA cylinders under an electric field. After removal of the PMMA minor component, a nanoporous film is formed. By electrodeposition, an array of nanowires can be replicated in the porous template (adapted from [43]). b Hexagonally packed array of aluminum caps generated from rod-coil microporous structures. Deposition of aluminum was achieved on the photooxidized area of the rod-coil honeycomb structure (Taken from [35])...

Chronopotentiometry. Paunovic and Oechslin (8) measured the adsorption of peptone on lead-tin alloy electrodes using chronopotentiometric and double-layer measurements. This case is different from the adsorption of HCOOH because peptone is not an electroactive species in the conditions smdied but only blocks the surface used for the electrodeposition of lead-tin alloys from solutions containing Sn and Pb ions. Chronopotentiometric analysis is based on the following principles (7). In the absence of adsorption, the relationship between the transition time r (for reduction of Sn and Pb in this case), the bulk concentration c° of the substance reacting at the electrode, and the current I is given by the equation... 

The blocking effect of ben2yl and substituted ben2yl alcohol additives on the electrodeposition of cadmium [220] and stabilization of cadmium electrode properties [221] were studied voltammetrically. 

The best electrodeposits of chromium are obtained from solutions of chromic acid containing small amounts of certain anions, particularly the sulfate ion. There is little doubt that the nature of the deposit is influenced by the formation of a complex chromic chromate diaphragm on the cathode. The function of the anion appears to be to affect the nature of this diaphragm in such a manner so that it does not block the cathode completely it thus does not prevent access of ions, yet it is suflftciently adherent to interfere with the growth of crystal nuclei. 

Silver electrodeposition was studied by different authors [6.75-6.78, 6.87-6.89]. An exact interpretation of EIS data was found to be only possible on the basis of partially blocked electrode surfaces. The high overall exchange current density of the Ag/Ag electrode requires a special high-frequency (HF) EIS technique [6.77, 6.78]. 

Seiter et al. [80] found a correlation between the overpotential and growth forms of electrodeposited copper on copper sheet substrate with (100) texture, as shown in Fig. 31. Barnes etal. [81] observed similar results on copper single crystal surfaces near (100) face below 10-mV ridges, 40-70-mV platelets, 70-100-mV blocks and fine platelets and above 100-mV polycrystalline deposit. 

The properties of the surface layers have a strong effect on the deposition process. The driving force of the electrochemical reaction is the potential difference over the electrochemical double layer. Adsorption of species can change this potential. For example, the additives used in electrodeposition adsorb in the Helmholtz layer. They can change the local potential difference, block active deposition sites, and so on. The thickness of the diffusion layer affects the mass-transfer rate to the electrode. The diffusion layer becomes thinner with increasing flow rate. When the diffusion layer is thicker than the electrode surface profile, local mass-transfer rates are not equal along the electrode surface. This means that under mass-transfer control, metal deposition on electrode surface peaks is faster than in the valleys and a rough deposit will result. 

Figure 2.4 Voltammetry demonstrating that a self-assembled Cn6-alkane thiol film effectively blocks nickel electrodeposition on a copper substrate. The inset shows that patterning methods, such as soft lithography, may be used to produce three-dimensional topographies by through-mask plating using an alkanethiol layer as a resist [96],...

Since the mid-1970s there has been a considerable amount of material published on the influence of ultrasound upon the electrochemistry of metal systems. Most of this work was carried out in former Eastern block countries and concentrated on such electrochemical processes as corrosion, electrodeposition, and electrochemical dissolution. Recently there has been an upsurge in the interest shown in sonoelectrochemical processes using both non-metal and metal systems worldwide. There have been a considerable number of publications in the employment of ultrasound in areas as diverse as semiconductor production to sono-electrochemical machining and metal finishing. A review by R. Walker [27] into the use of ultrasound in metal deposition systems, provides an introduction into the fundamental effects of ultrasound in plating and metal finishing. 

Areas of passivation, corrosion, and immunity in aqueous systems can be seen in Fig. 3.23. Accordingly, electrodeposition of tungsten is only possible when the hydrogen formation is blocked. However, this will not only be influenced in practice by thermodynamic but also by kinetic properties. Therefore, it is only possible to deposit tungsten... 

Pricer, Kushner, and Alkire" used Monte-Carlo type stochastic methods for modeling the filling of vias and trenches by electrodeposition in the presence of a hypothetical blocking additive. Random numbers were used to determine when and if a particle would make a certain move." Each move for a species had a probability value associated with it that depends on the time step. This Monte-Carlo computer program had 14 parameters related to the additive, Cu and Curious. An analysis of Monte Carlo snapshots during trench filling resulted in a series of conclusions. We are presenting here only two ... 

In the first set of experiments, we investigated copper electrodeposition on micropattems with different aspect ratios in the presence of sulfuric acid. Figure 20.12 shows the results for an applied potential of —0.2 V. The effect of hydrogen bubbles is evident the bubbles block the microtrenches... 

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