Improved dense via yields of Cu/CVD low k CoralTM dual damascene metallization at post Cu cap etch wet clean

130 nm technology uses Cu/low k materials integration for the back-end-of-line (BEOL) process. The motivation of this work is to improve the electrical performance of Cu/CVD low k Coral(TM) dual damascene metallization through optimization of the Cu cap etch wet clean. Two types of wet clean chemicals (amine- and fluoride-based mixtures) were selected for the study, using either a conventional batch spray process or single wafer cleaning system. The single wafer cleaning system provides an efficient means of removing polymeric residues (especially the via sidewall and bottom) with the application of mega-sonic acoustic agitation. On the whole, we achieved excellent physical, electrical and burn-in reliability results for the interconnects processed from single wafer cleaning system with ST250(TM) at post Cu cap etch. The fabricated wafers achieved electrical yields 95% for the dense via chains before and after 500 h burn-in reliability tests.