SURFACTANTS AND SURFACE ALLOY FORMATION IN ALLOY ELECTRODEPOSITION

 

Dincer Gokcen, Thomas P. Moffat

 

Surfactants play a central role in the electrochemical processing of thin film materials. The surfactants can influence both the rate of film growth and the resulting microstructure. In many cases, multiple surfactants may be employed, and the competition for surface sites may act to template growth accordingly. In certain instances, the surfactants may even be incorporated into the growing film. In this presentation, the effect of underpotential deposition of Pb, a low surface tension metal surfactant, on Cu electrodeposition from a Cl- containing electrolyte will be examined. The Cl- anion is also a surfactant and the relative coverage (and surface structures that arise from the competition between Pb and Cl- will be detailed based on in situ scanning tunneling microscopy (STM) experiments and electroanalytical measurements. The influence of the surfactants on the electrodeposition of Cu on highly textured Cu(100)/Si(100) will be described and the role of surfactant action as well as surface alloy formation and kinetic trapping (i.e. d-doping) in formation of supersaturated Cu-Pb alloys will be detailed based on SEM, EDS and XRD measurements.