Fabrication of an ultra-thin low resistance and high stability Ru–Mo–C seedless barrier for advanced Cu dual-damascene interconnects

Abstract

Cu dual-damascene interconnects with an amorphous Ru–Mo–C (labeled as RuMoC) seedless barrier layer were successfully fabricated and its feasibility for advanced Cu dual-damascene interconnects were investigated. The results show that the RuMoC II films obtained with sputtering rates (Ru:MoC) of 100:50 demonstrated the best performance, exhibiting an amorphous structure, low residual oxygen content, low resistivity at temperatures up to 500 °C. A Cu plug of good quality was successfully electroplated on the RuMoC II barrier layer with 4-nm-thick without seed layer in a damascene structure. The ultra-thin RuMoC II barrier effectively blocked the diffusion of Cu and O atom after being annealed up to 500 °C. The damascene structure showed much lower leakage current and via resistance compared to the damascene structures with traditional Ta barrier, suggesting that RuMoC II film has sufficient barrier properties. Moreover, the via resistance of the damascene structures with RuMoC II barrier were quite low and met the requirement of different technology nodes for the future semiconductor industry, indicating great prospects for advanced seedless Cu metallization applications.