Inductively coupled plasma etching of (Ba,Sr)TiO₃ thin films

Etching behaviors of (Ba,Sr)TiO₃ (BST) thin films were studied by an inductively coupled plasma (ICP). Using Cl₂ gas with Ar gas, etch rate of the BST thin films and their selectivity for SiO₂ hard masks were systematically investigated over a wide range of gas mixing ratio and ICP power. The films were etched at rates of 400 Å/min using 20% of Cl₂ flow and 80% of Ar flow under ambient pressure below 10 mTorr and at a reactive ion etch power of 150 W and at an ICP power of 700 W. Chemical analysis by Auger electron spectroscopy showed that postetch residues had Ba- and Sr-rich phases which were not found on the surface of the SiO₂ hard mask. It was found that the residues of the BST films can be removed with the addition of SF₆ gas in the etchant gas mixture. © 1998 American Vacuum Society.