Electrochemical Engineering

Richard Alkire, Paul Kenis

Many products are appearing for which quality is dominated by precise control of chemical and material properties at atomic-to-submicron dimensions. While new experimental tools are leading to remarkable advances in fundamental understanding of events at electrode surfaces down to the molecular scale, current electrochemical engineering models are based on continuum equations and, therefore, lack adequate 'boundary conditions' associated with atomic-to-submicron scales. As a consequence, current electrochemical engineering design, control, and optimization procedures have blind spots in the precise region where product quality is determined.

electron microscope image of electrodepositionElectrodeposition of copper is a crucial area of study due to the shift from aluminum (Al) to copper (Cu) for on-chip interconnections, which represents one of the most important changes in materials that the semiconductor industry has experienced. Copper electrodeposition has recently become a chief technological process route for applications in semiconductor interconnects owing to improved clock speed, reliability, and cost. Product quality is determined by the role of additives at the molecular scale where they act to impart remarkable shape control and deposit properties. Although the effect of additives on morphology evolution is widely studied, current knowledge of additive behavior is insufficient for future microelectronic process requirements. The rapid innovation of new additive systems will require close integration of newly emerging science with improved engineering simulations and process innovations.

A major area of study in Prof. Alkire's laboratory is to develop computational and experimental methodologies to determine the microscopic mechanisms of additives in copper electrodeposition. The effort will contribute to a larger project aimed at linking mathematical models of molecular hypotheses to procedures used to guide engineering design. We accomplish this goal by developing a collaborative computational and experimental approach that (1) links experimental expertise with numerical simulations over broad time- and distance-scales, (2) makes results accessible to the non-expert, and (3) takes strategic advantage of high performance computing.

Recently, Kenis and Alkire have begun developing arrays of micro-electrochemical systems for the rapid screening of a wide variety of additives to be used in electroplating or for the study of surface corrosion of metals.