Impact of Dry Etch and Ash Conditions on Removability of Plasma Etch Residues in Al-Metallization. Approach to Improve PER Cleaning Efficiency by EHS-Friendly Aqueous Remover
Driven by cost saving pressure and new regulations such as REACH, the imple¬mentation of cost efficient, EHS-friendly alternatives is in full swing. There is a clear trend in the plasma etch residue (PER) cleaning field to replace the currently used, expensive and harmful organic PER-removers by EHS-friendly aqueous alternatives. Striking advantages of fluorine free aqueous removal are reported1. The goals of present work -which was carried out in cooperation of BASF and Infineon-, was to examine the dependence of residue constitution on etch and strip conditions and to find a way to adapt also most critical cleaning challenges for EHS-friendly PER remover usage. For that reason a selected aluminum interconnect metal layer with difficult removable residues was chosen. XPS is well proved as an appropriate method for selective sidewall and top/bottom residue analysis2. Our analytical work was focused on defining fingerprints for the etch residues, concerning their elemental distribution, and tracking their changes during the different process steps and conditions.
Paul Mertens, Marc Meuris and Marc Heyns
B. Ferstl et al., "Impact of Dry Etch and Ash Conditions on Removability of Plasma Etch Residues in Al-Metallization. Approach to Improve PER Cleaning Efficiency by EHS-Friendly Aqueous Remover", Solid State Phenomena, Vols. 145-146, pp. 353-356, 2009