Impurity Study of Copper Film Fabricated by Electroplating with Supercritical Carbon Dioxide Emulsified Electrolyte

Abstract

Impurity content in the copper films fabricated by electroplating with supercritical CO₂ emulsified electrolyte (EP–SCE) and supercritical CO₂ suspension (EP–SCS) is studied by glow discharge optical emission spectroscopy to reveal the feasibility to apply EP–SCE and EP–SCS in copper interconnect technology. Distributions of carbon from top surface to interface between the electroplated copper and the substrate in copper films fabricated by EP–SCE and EP–SCS are similar to those of films fabricated by the conventional electroplating (CONV). Distributions of oxygen in the films fabricated by EP–SCE and EP–SCS are also similar to those of films fabricated by the CONV. The results confirm the CO₂ and surfactants used in the EP–SCE and EP–SCS would not cause any impurity problems in applications.