Effect of crystallinity and preferred orientation of Ta₂N films on diffusion barrier properties for copper metallization

Tantalum nitride (Ta₂N) films deposited at various substrate temperatures onto silicon (001) substrates can produce amorphous and crystalline phase with different preferred orientations. Subsequently, the viability of employing them as the diffusion barriers between copper and silicon is investigated by annealing at various temperatures for 30 min. The characterization of the thin films was carried out by four-point probe and X-ray diffraction. The results indicate that the thermal stability of Ta₂N with Cu and Si are dependent on the crystallinity of Ta₂N. Ta₂N phase with the highest (002) preferred orientation exhibits the highest structural stability to prevent copper diffusion more effectively.