This Interface article is based on presentations at the 242(nd) ECS Meeting in Atlanta, in the centennial symposium "E04 - 100 Years of the Electrodeposition Division: Past, Present, and Future," given on Wednesday October 12, 2022.

The development of electrodeposition practice and the underlying science and engineering methods that emerged during the past century will be traced. Beginning in the late 19 th century, many large-scale electrolytic technologies became feasible owing to the invention of the electric generator. These included electrowinning, electrorefining, and electrodeposition, among others. Their early development and commercial use took place before the recognition of many fundamental scientific and engineering principles. As a result, these industries came to be characterized by slow evolutionary change based on past experience and intuitive insight. In 1913, a symposium on electrodeposition was arguably the first to apply systematic academic effort to the art of the plater, and thus promote cooperation between science and technology. The success of these activities led, in 1922, to formation of the Electrodeposition Division. For several subsequent decades, the growth of electrodeposition technology took place while electrochemists developed experimental tools (e.g. polarography), data (e.g., thermodynamic) and theories (e.g. non-ideal electrolytic solutions). By the 1950s there were an enormous number of electrodeposition applications, but the sense was emerging that progress based on empirical experimentation was rapidly coming to a close, and that further significant advances could be made only when the fundamentals of the plating processes are more completely understood. During the 1960s, the invention of new materials revolutionized the electrodeposition industries. In addition, the digital computer came into use for obtaining the current distribution in simple geometries. In addition, refined experimental research methods were developed, iincluding the potentiostatic power supply, rotating disk, “model” experimental systems, and various electroanalytical and surface-science techniques, In the 1970s, the field of electrodeposition technology saw significant new demands arising from changed availability of energy, feedstock, and capital as well as increased attention to waste treatment. These events shattered the empirical traditions of the past, and triggered new interest in ‘modern’ electrodeposition science and engineering built o a foundation of thermodynamics, kinetics, transport phenomena, and current distribution aspects. In the 1980s, the magnetic thin-film storage head, energized the entire microelectronics field of electrodeposition technology. Also, studies with single crystal electrodes and with surface scanning microscopies provided spectacular new capabilities for investigations at time scales, molecular specificity, and spatial resolution that were orders of magnitude superior to those of only a decade earlier. By the 1990s, important advances were made in understanding phenomena associated with defects, additives, solvent effects, nanoscale phenomena, surface films, mechanisms of lattice formation, among others. In addition, mathematical modeling of electrodeposition systems moved down-scale to include both continuum and non-continuum phenomena. During the 2000s, the shift from aluminum to electrodeposited copper for on-chip interconnections represented one of the most important change in materials since the beginning of the semiconductor industry. In the 2010s, the mathematical tools used to explore electrochemical systems expanded beyond the traditional continuum methods to include kinetic Monte Carlo, molecular dynamics, and quantum chemistry. In conclusion, throughout the history of electrodeposition science and technology, several high-level trends may be recognized: Advances often came from outside the electrodeposition field. It is important to read the literature widely, and with enough informed judgment to recognize analogies between seemingly different situations; Many electrodeposition systems have been improved over the course of many years. The literature contains a gold mine of applications worth further study. It is important to recognize when new science or engineering materials and methods can provide fresh insights to improving old, but very important, applications; Over the past century, there have been periods when significant gaps existed between scientific understanding of electrochemical phenomena, and our ability to incorporate it into engineering practice. It is important to identify problems worth solving and to release impedements to introduction of new ideas. Today, the ability to use numerical simulations to achieve precise quantitative understanding at new levels of magnitude, sophistication, and completeness offers a significant challenge. It is therefore important to develop re-usable electrochemical engineering methods, and to align tight integration of discovery science, application design, research prototyping and manufacturing collaboration.

Scientific discoveries and inventions are driving novel technological concepts that demand unprecedented control at the microscopic scale during processing. Challenges arise because critically important events occur at the atomistic scale, while the corresponding technological processes are designed to operate and be controlled at the macroscale. New approaches are therefore needed that couple traditional engineering design methods with non-continuum stochastic phenomena. This work provides perspectives on what is needed to implement deep integration of engineering design procedures with molecular-scale knowledge. (C) The Author(s) 2019. Published by ECS.

Professor Dieter M. Kolb, Director of the Institute of Electrochemistry at the University of Ulm from 1990 to 2010, passed away on October 4, 2011, following a severe illness. Dieter Kolb was born on October 11, 1942 in Amberg, Germany, where he spent his early childhood, before his family moved to Munich, where his father served as a judge. In 1961, he enrolled at the Technical University of Munich to study physics. He carried out his Diplom research under the supervision of his lifelong mentor, Professor Heinz Gerischer, at the Institute of Physical Chemistry, investigating radical reactions using ESR spectroscopy. In 1969 he completed his doctoral work under Professor Gerischer on the homogeneous catalysis of radical reactions in aromatic nitro compounds. In 1971, following a postdoctoral appointment at the renowned Bell Laboratories in New York, Dieter Kolb became a group leader in Berlin, where he once again worked with Heinz Gerischer, who was now director of the Fritz Haber Institute. During this time, he carried out his pioneering work on underpotential deposition of foreign metals on electrode surfaces.1, 2 In 1976 Dieter Kolb completed his habilitation in Physical Chemistry at the Free University of Berlin, where he was appointed Professor of Chemistry in 1984. On September 1, 1990, Dieter Kolb moved to the University of Ulm, as Professor of Physical Chemistry and Director of the Institute of Electrochemistry. Under his direction, electrochemistry research at the University of Ulm rose to international prominence. In 2011 Professor Kolb was named a director at the newly formed Helmholtz Institute Ulm for Electrochemical Energy Storage. Professor Timo Jacob now serves as his successor at the University of Ulm. Kolb gained a worldwide reputation for his groundbreaking contributions to our fundamental understanding of electrochemical processes. While his scientific work covered a wide range of topics over the years, his research is especially characterized by its exploration of the interplay between the atomistic surface structures of electrode materials and the electrochemical reactions taking place on them. Thus, he took full advantage of the techniques of modern surface science to explain the classical phenomena of electrochemistry in terms of the atomistic structures at the liquid–solid interface. The high quality of his experimental measurements is well-known in the electrochemistry community, and his atomic-resolution in-situ scanning tunneling microscopy (STM) images of electrode surfaces have stood at the forefront of the development of modern, experimental electrochemistry.3 His research interests included electrocatalysis,4 investigations of organic overlayers,5 the characterization of nanostructures using STM, and the new field of ionic liquids in electrochemistry. Thus, his pioneering spirit has paved the way for the next generation of scientists to advance even further in the field of electrochemical surface science.6, 7 Dieter Kolb played an active role in the German Bunsen Society for Physical Chemistry, as well as in the International Society of Electrochemistry, serving as President of the latter from 2003 to 2004. The extent and importance of his scientific accomplishments is reflected in the numerous awards and honors with which he was recognized. Among these are the Pergamon Gold Medal and Olin Palladium Award from the International Society of Electrochemistry, the D. C. Grahame Award from the Electrochemical Society, and the Faraday Medal from the Royal Society of Chemistry. In September 2011, Dieter Kolb was awarded the Frumkin Memorial Medal by the International Society of Electrochemistry in honor of his life’s work in the field of electrochemisty. He was particularly delighted to receive this award, as for him it represented the final recognition of the significance his contributions to the international electrochemistry community. Dieter Kolb’s doctoral adviser, Heinz Gerischer, was a co-worker of Karl Friedrich Bonhoeffer, who in turn had studied under Walter Nernst and Wilhelm Ostwald. Thus, he found himself following in the footsteps of these two eminent founders of physical chemistry. Dieter Kolb’s rich contributions to electrochemistry and classical physical chemistry do full justice to his scientific pedigree, and it is fitting that he too takes his place in the ever growing tradition of physical chemistry. His extensive knowledge of electrochemistry stemmed not only from the results of his own experimental research, but also from a thorough study of the literature. His expertise was widely sought out in scientific discussions, and he was looked to as an authority in the field of electrochemistry. He was a great promoter of young, developing scientists, and had a knack for quickly identifying his students’ strengths and supporting them accordingly. Dieter Kolb took his highly esteemed mentor Professor Heinz Gerischer as his own scientific role model. After Gerischer’s death in 1994, he, along with other colleagues, organized the Gerischer Symposium, which meets every three years in Berlin to address fundamental issues in electrochemistry. Furthermore, Dieter Kolb followed in Gerischer’s footsteps by assuming the editorship of “Advances in Electrochemistry and Electrochemical Engineering” together with Richard Alkire. In 1993 his wife Franziska passed away, far too soon. In her memory, Dieter Kolb founded the Franziska Kolb Foundation for the Support of Leukaemia Research, and then he gave himself over to his scientific work even more fully than before. Since that time he considered the members of his Institute of Electrochemistry to be his family. Professor Kolb stands among the eminent scientists who have left their mark on the field of chemistry. Many friends and colleagues esteem him highly as an academic, but even more as a unique and extraordinary individual. He will be sorely missed within the electrochemical community.

On-chip fuel cells are promising power sources for future electronics and microdevice applications including on-chip sensors and micro-air-vehicles. Previously, we reported a small scale (0.4 mm wide and 6 mm long) on-chip fuel cell of an air-breathing, membrane-less and monolithic design, which exhibited the highest power for an on-chip fuel cell, 1.4 mu W (J. Am. Chem. Soc., 2008, 130, 10456). In order to improve the performance, precise understanding of the phenomena occurring in the cells is of primary importance. Thus, this paper focuses on understanding cell operation by using numerical simulation, and on implementing cell improvements based on the simulation results. The initial quantitative study concluded that the performance of the on-chip fuel cell was limited owing to oxygen-supply caused by cathode flooding. Thus, we experimentally added the hydrophobic ionomer (Nafion) onto the cell to reduce the influence of the flooding, and successfully increased the maximum power from 2.0 to 2.8 mu W. This power is considered sufficient for microsensor application. On the basis of additional simulation results, we show that performance may potentially be improved to over 100 mu W by increasing the effective surface areas of catalysts to a level comparable with methanol fuel cells. If successful, such performance enhancements would position the on-chip fuel cell as a viable candidate for future micro-devices, and point to promising directions for fuel cell development efforts.

The "island dynamics" method was applied to simulation of kinetically limited metal nucleation and growth by electrodeposition in the presence of additives. The model includes additive kinetics (described by a set of ordinary differential rate equations), surface diffusion of adatoms (calculated with a continuum equation), and nucleation (calculated by a rate equation that depends on average adatom concentration and diffusivity). Nuclei are placed on the surface stochastically at locations weighted by the local value of adatom concentration. The moving interface is tracked by the level-set method. The model was demonstrated for copper deposition in acid-sulfate electrolyte containing [bis(3-sulfopropyl)disulfide], polyethylene glycol, and chloride. Numerical results were obtained for fractional coverage of additive species and reaction intermediates, coverage of metal deposit on the surface, and spatial information on nuclei, islands, and multilayer structures. Simulation results were compared with kinetic Monte Carlo (KMC) calculations and found to be within 1% for fractional coverage values and within 10% for nucleation density. The computational speed was 10-30x higher than comparable KMC simulations over the range studied. The accuracy and computational speed of the island dynamics algorithm captures phenomena present at widely varying length and time scales which are needed for molecular engineering of electrodeposition processes.

Nucleation and growth in the presence of additives during Cu electrodeposition on ordered arrays of Cu seed Clusters oil a polycrystalline An film were investigated. The seed Clusters, formed by an E-beam lithography method, were 25 nm in diameter and positioned in square arrays (100, 200, or 300 nm spacing) with overall dimensions of 20 x 20 mu m. Electrodeposition was carried out in acid sulfate solutions (0.6 M CuSO4 and 1.0 M H2SO4) containing various concentrations of additives [0.1-10 ppm Cl-, 3-3000 ppm poly(ethylene glycol), and 3-50 ppm bis(3-sulfopropyl) disulfide]. Image analysis methods were used to extract quantitative information oil the effect of additives, array spacing, and potential on the probability of finding Cu nuclei at a given distance from a Cu seed cluster as well as finding the nearest neighbor to any deposited Cu nucleus. The level of chloride concentration was found to mediate the extent of seed growth vs wild nucleation. Low levels of chloride (0.1 ppm) yielded growth predominantly at the Cu seeds with virtually no wild nuclei. Progressively higher levels of chloride (1 and 10 ppm) yielded lower deposition rates at the Cu seeds and proportionally higher levels of wild nucleation. Experimental results are compared with numerical simulations in Part II [Stephens et al., J. Electrochem. Soc., 156, D385 (2009)]. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3183502] All rights reserved.

Electrochemical phenomena control the existence and movement of charged species in the bulk, as well as across interfaces between, ionic, electronic, semiconductor, photonic, and dielectric materials. The existing technology base of the electrochemical field is massive and of long-standing, dating to the earliest days of chemical process industry. The pervasive occurrence of electrochemical phenomena may also be seen today in nanoscale and biological systems, in microelectronic devices, and in green processes as well as in natural systems. Consider several examples: • Materials include metals, alloys, ceramics, ionic solids, semiconductors, membranes, coatings, colloids, conducting polymers, and biological materials including proteins and enzymes. • Phenomena that arise include conduction, potential field effects, electron or ion disorder, electroluminescence, ion exchange, passivity, membrane transport, double layers at boundaries between phases involving free charges, osmotic flow, and electrokinetic phenomena. • Processes that depend critically on these phenomena include energy storage and conversion, corrosion, membrane separations, electrodeposition, etching, desalination, electrosynthesis of chemicals, refining of metals, and many others. • Products that result include microelectronic devices, sensors, batteries, fuel cells, coatings, films, metals, gases, chemicals, and ceramics. During the early yars of the past century, each electrochemical technology was tuned to the economic and technical realities at hand, similarities among many different processes were eventually be recognized, the most significant being that, for economic reasons, large-scale electrolytic processes are invariably driven to a transport-limited rate. Therefore, the electrochemical engineering research literature of the past half century focused strongly on understanding how ohmic and mass transport processes, including the effect of hydrodynamic flow, influence the potential field between electrodes as well as the current distribution, or rate of electrochemical reaction along a surface. All structural metals are thermodynamically unstable and corrode by virtue of local anodic and cathodic regions that are driven by the energy contained in their local environment. The annual cost of corrosion in the US has been recently estimated to be $276B, or 3.1% of the US Gross Domestic Product. The design principles for corrosion, however, are very different from those used in materials processing since, when you succeed in corrosion, nothing happens. The key requirement is to understand how failure occurs, and then to design so as to intervene. Beginning in the 1950's, mathematical modeling of the current and potential distribution in electrochemical systems including corrosion advanced steadily at the continuum level where sophisticated simulations are by now widely used to predict behavior needed for engineering design, scale-up, optimization, and process control. Continuum codes dominate the extensive modeling literature in electrochemical systems. A wide variety of phenomena can be included with the result that models are widely used for sorting out competing effects, resolving experimental data, articulating scientific hypotheses of mechanism, measuring system parameters, and predicting behavior. Such models provide a rational basis for engineering design, optimization, and control. Generally, however, they have until only recently been based on empirical characterization of the interfacial processes that appear as boundary conditions in the transport analyses. During the past several decades, the field has evolved rapidly based primarily on a suite of remarkable new tools that provide the ability to create precisely characterized systems for fundamental study; to monitor behavior at unprecedented levels of sensitivity, atomic resolution, and chemical specificity; and to predict behavior with new theories and improved computational abilities. These capabilities have revolutionized fundamental scientific understanding of interfacial and catalytic processes, as well as contributed to the present rapid pace of discovery of novel materials and devices where product quality is determined at the molecular scale. To drive new electrochemical discoveries toward technology innovation, new engineering methods are needed in order to ensure product quality at the molecular scale. Recent advances in computer speed and memory, numerical algorithms, and sensor technologies indicate clearly that a systematic approach is possible that integrates scientific knowledge, intuition, experimental data, and simulations. However, today's engineering design tools are based on continuum phenomena and therefore have a blind spot at the molecular scale. In addition, the primary manipulation of operating conditions during manufacturing today occurs at macroscopic length scales. A new generation of science and engineering design methods must emerge to integrate discoveries, concepts, theory, and experimental data with process engineering in order to design and control future multiscale electrochemical systems. The challenges to building such tools include uncertainties in the physicochemical mechanisms as well as the values of thermodynamic and kinetic parameters, complexities in the simulation of model equations that can span a wide range of time and length scales, lack of manipulated variables and direct measurements of most properties at the nanoscale during processing, and the inapplicability of most existing systems tools to address systems described by noncontinuum and dynamically coupled continuum-noncontinuum models. These challenges specify the requirements for next-generation tools needed for a systematic approach to the design and control of electrochemical systems from molecules to devices. The ability to use multiscale, multi-phenomena numerical simulations to achieve precise, quantitative understanding at new levels of magnitude, sophistication, and completeness offers a challenge for electrochemical engineering which, when met, will bring enormous benefits through rapid innovation as well as improvements in existing technological applications.

Electron-beam-induced deposition was used to create an ordered array of Pt seed clusters on a Au film onto which Cu was subsequently electrodeposited in the presence of additives. The Pt seed clusters were 25-30 nm diameter, positioned in square arrays of 200, 300, or 400 nm spacing, with overall dimensions of 5 x 5 mu m. Electrodeposition was carried out in an acid sulfate bath containing additives. Image analysis methods were used to evaluate the probability of finding Cu nuclei at a given distance from a Pt seed cluster, as well as finding the nearest neighbor to any deposited Cu nucleus. (C) 2008 The Electrochemical Society. [DOI: 10.1149/1.2992705] All rights reserved.

The introduction of the electrical dynamo in the early 1870s made large scale, relatively inexpensive electric power available for commercial scale chemical production.

Product quality variables for many electronics and materials processes are set at the nanoscale and smaller length scales. Although the control of these processes is of scientific and industrial interest, there is a shortage of feedback controller design methods based on the noncontinuum models that describe such nanoscopic phenomena. In this study, linear, gain-scheduled, and nonlinear feedback controllers are designed for a coupled kinetic Monte Carlo-finite difference code that simulates the manufacture of copper interconnects. The feedback controller designs incorporate a low order stochastic model constructed from the coupled continuum-noncontinuum code

The need for electrochemical engineering arises in society because of technological applications that involve electrochemical phenomena such as synthesis of chemicals, electrowinning and refining of metals, power sources, sensors, surface modification by electrodeposition and etching, separations, and corrosion, to mention a few. Each of these involves components (electrode, electrolyte, separator, etc.) that are tuned in response to prevailing economic variables (such as cost of investment, power, raw materials, product quality) by skillful manipulation of engineering design variables (such as cell materials, cell reactions, current, electrode area, cell voltage, conversion, product quality).

The purpose of this presentation is to provide a selective overview of science and engineering aspects of morphology evolution, and to suggest areas where strategic advances will benefit a broad range of specific technologies. Recent advances in experimental and computational approaches for both continuum and non-continuum regions of behavior are presented for the study of additive effects on copper morphology evolution during electrodeposition. In microelectronic applications, deposit quality is determined on the molecular scale by the action of additives. Emphasis is therefore placed on integration of experimental data and qualitative hypotheses with computational strategies in order to understand behavior at the non-continuum level. In addition, emphasis is also given to the linkage of non-continuum simulations with traditional electrochemical engineering tools that use continuum methods to compute potential and current distribution phenomena in macroscopic systems. The use of multiscale, multi-phenomena numerical simulation offers promise for speeding innovation as well as design of advanced technological applications.

The role that Al{sub 3}Fe intermetallic inclusions play during initiation of pitting corrosion on aluminum alloys was investigated in 0.6 M NaCl. In aerated solutions microscopic observations showed the growth of cavities in the host metal adjacent to inclusions. The rest potential of synthetic Al{sub 3}Fe was measured in aerated and deaerated NaCl solutions over a range of bulk pH values between 2 and 12 and was found to act as a cathode. In aerated solutions rotating disk electrode experiments on synthetic Al{sub 3}Fe electrodes verified that the cathodic reaction corresponded to the reduction of dissolved oxygen. With scanning pH microelectrodes, measurements were carried out near synthetic Al{sub 3}Fe electrodes which were coupled in a galvanic cell with Al-6061 in NaCl solution. In addition, the pH measured over Al-6061 at a distance of 25--30 {micro}m from the surface was observed to fluctuate between pH 4 and 8.5 for the first 2 h of immersion in NaCl solutions. Atomic force microscopy images of Al-6061 immersed in buffered aerated 0.6 M NaCl solution (pH 5.5) did not show any evidence of dissolution of the Al around intermetallics. These measurements support the view that Al{sub 3}Fe particles in Al-6061 serve as local cathodes,more » that a high pH develops around the intermetallic particles by dissolving alkaline cavities to evolve into a small number of rapidly dissolving acidic pits.« less