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

The etch characteristics of iridium. thin films with a photoresist mask wer e studied by varying the etch chemistries in an inductively coupled plasma. The etch rates and etch profiles of iridium films were investigated with r espect to etch gases, which included Cl-2/Ar, SiCl4/Ar, C2F6/Ar, HBr/Ar, an d C2F6/Cl-2/Ar mixtures. Fluorine-containing gases were the most effective in achieving clean etch profiles without any redeposition or residue. Howev er, 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 spect roscopy was employed for the analysis of the redeposited materials and tran sient etch profiles by time progression were observed by scanning electron microscopy. It can be concluded that iridium films are etched. mainly by ph ysical 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 degre es was obtained by using a gas mix of C2F6, Cl-2, and Ar. (C) 2001 American Vacuum Society.