Effects of thermal annealing on Zr–N doped magnetron sputtered copper

A barrierless metallization scheme was proposed using Cu-based materials with enhanced thermal stability. Cu(Zr–N) films were deposited on Si substrates by magnetron sputtering and annealed at temperature up to 500 °C in vacuum. The beneficial effects of a minor insoluble Zr–N on the grain refinement and thermal stability improvement were confirmed. By doping insoluble Zr–N into pure copper, some of the additive atoms precipitate at the grain boundaries, which can block the path of diffusion between copper and silicon, and inhibit the interaction between copper and silicon. In addition, ZrO2 or Zr(N,O) development near the Cu(Zr–N)/Si interface during annealing also contributes to the thermal stability of Cu(Zr–N)/Si samples. The results of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and sheet resistance measurement show that Cu(Zr–N) seed layers has better thermal stability after 500 °C annealing and is suitable for advanced barrierless metallization.