The Application of Barrierless Metallization in Making Copper Alloy, Cu(RuHfN), Films for Fine Interconnects

Abstract

In this study, films of a copper (Cu) alloy, Cu(RuHfNx), were deposited on silicon (Si) substrates with high thermal stability by co-sputtering copper and minute amounts of Hf or Hf/Ru in an Ar/N2 gas mixture. The Cu(RuHfNx) films were thermally stable up to 720°C; after annealing at 720°C for 1 h, the thermal stability was great enough to avoid undesired reaction between the copper and the silicon. No copper silicide was formed at the Cu–Si interface for the films after annealing at 720°C for 1 h. The Cu(RuHfNx) films appear to be good candidate interconnect materials.