Etch characteristics of iridium in chlorine-containing and fluorine-containing gas plasmas

The etch characteristics of iridium. thin films with a photoresist mask were studied by varying the etch chemistries in an inductively coupled plasma. The etch rates and etch profiles of iridium films were investigated with respect to etch gases, which included Cl-2/Ar, SiCl4/Ar, C2F6/Ar, HBr/Ar, and C2F6/Cl-2/Ar mixtures. Fluorine-containing gases were the most effective in achieving clean etch profiles without any redeposition or residue. However, the etch rate of iridium was found to be faster in chlorine-containing gases than in any of the others tested. Field emission auger electron spectroscopy was employed for the analysis of the redeposited materials and transient etch profiles by time progression were observed by scanning electron microscopy. It can be concluded that iridium films are etched. mainly by physical sputtering in chlorine-containing gases and by a chemically assisted sputtering etching component in fluorine-containing gases. A residue-free iridium etching with a sidewall angle of approximately 45 degrees -50 degrees was obtained by using a gas mix of C2F6, Cl-2, and Ar. (C) 2001 American Vacuum Society.