(Invited) Critical Copper Line Scaling Challenges

The demand for low resistance metallization solutions has become an increasingly important issue as interconnect line sizes have approached and in some cases become smaller than the electron mean free path in Cu. Formation of reliable small damascene Cu features with high aspect ratio pose major challenges to void free Cu fill process development. Surfaces and interfaces now begin to play a more dominant role in scaled interconnects, with critical defect sizes becoming much smaller than before. Interfacial engineering between copper and liner/seed, liner/seed to barrier, as well as critical defect control from galvanic corrosion and CuOx nodule formation are also key components of successful metallization development. In this paper, we discuss some critical copper process challenges, focusing on copper barrier/liner, seed, fill, heat treatment, CMP and clean processes development to attain low resistance and reliable metallization.