Cu wiring into nano-scale holes by electrodeposition in supercritical carbon dioxide emulsified electrolyte with a continuous-flow reaction system

Abstract

In this paper, a continuous-flow reaction system was proposed and examined for filling of Cu into holes with 60nm in diameter and aspect ratio of 2 and 5 by an electroplating method with supercritical carbon dioxide (sc-CO2) emulsified electrolyte on a round-type large-area hole test element group (TEG) with diameter of 300mm, which has an integrated structure of Cu seed layer on TiN barrier layer sputtered on Si substrates. Copper-sulfate-based electrolyte was used and emulsified by sc-CO2 and a surfactant and Cu particles was added to create a suspension. 313K and 12MPa were used with various applied current density (1.41, 2.83 and 4.23A/dm2). The TEG was found to be completely covered by electrodeposited Cu when 2.83A/dm2 was used. All of the holes were filled by Cu without any voids at 2.83A/dm2, while incomplete filling was observed at 1.41 and 4.23A/dm2. Moreover, a contamination of carbon was not detected by glow discharge optical emission spectroscopy and the reaction was suggested to be feasible to apply into Cu wiring.