The manufacturing of semiconductor devices involves electrodeposition of copper interconnects from additive containing electrolytes. The process depends on additives that affect the local deposition rate to yield void-free superconformal or bottom–up filling of trenches and vias. Useful quantitative surfactant conservation models are available for describing the filling of high aspect ratio features ranging from nanometers (on-chip wiring) to micrometers (through-silicon-vias) to millimeters (printed circuit boards). This includes the curvature enhanced adsorbate coverage (CEAC) model as well as the additive derived S-shaped negative differential resistance (S-NDR) description of film growth and feature filling. Nonetheless, much remains to be known about the operational limits of these constructs as well as the molecular nature of the competitive, co-adsorption dynamics of the additives and their impact on metal deposition. This lecture will detail recent experiments that reveal the important role of competitive, co-adsorption of polyether, Cl-, SPS and LEV additives in controlling the hydrophilicity of the interface and thereby the rate of metal deposition and its morphological and microstructural evolution.