Dry Etching Technique for Subquarter‐Micron Copper Interconnects

A dry etching technique for subquarter-micron Cu interconnects has been developed. A self-aligned passivation film on sidewalls of Cu lines is formed during etching. The thickness of the sidewall film composed of SiON can be controlled precisely by the composition of the etching gas mixture. The addition of NH 3 to the etching gas mixture of SiCl 4 /Cl 2 /N 2 results in a sidewall film free of chlorine. Therefore the sidewall film acts to protect Cu from oxidation and corrosion, and sustains the multilayered structure without film peeling during the fabrication process