화학공학소재연구정보센터
Industrial & Engineering Chemistry Research, Vol.50, No.13, 8080-8085, 2011
Defect-Free Nickel Micropillars Fabricated at a High Current Density by Application of a Supercritical Carbon Dioxide Emulsion
Fast transport properties, extremely low surface tension, and nonpolar property of supercritical carbon dioxide (Sc-CO2) are the key advantages of applying Sc-CO2 in heterogeneous reaction like electroplating. Hydrogen gas bubbles have been found to be a cause of defects found in materials fabricated by electroplating. The physical limitation at the bottom of the photoresist patterns increases the difficulty for removal of hydrogen gas bubbles and diffusion of reactant species to the reaction site. Therefore, low current density is usually applied to prevent formation of defects, but it also leads to low growth rate. Fabrication of defect-free Ni micropillars at a high current density has been demonstrated by application of Sc-CO2 emulsified electrolyte in this work. The average growth rate of the Ni micropillars in this study was about 4.7 mu m/min. Diameters of the electroplated Ni micropillars ranged from 50 to 125 mu m.